/* Vectorizer Specific Loop Manipulations
   Copyright (C) 2003-2024 Free Software Foundation, Inc.
   Contributed by Dorit Naishlos <dorit@il.ibm.com>
   and Ira Rosen <irar@il.ibm.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "tree-pass.h"
#include "ssa.h"
#include "fold-const.h"
#include "cfganal.h"
#include "gimplify.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "tree-cfg.h"
#include "tree-ssa-loop-manip.h"
#include "tree-into-ssa.h"
#include "tree-ssa.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-vectorizer.h"
#include "tree-ssa-loop-ivopts.h"
#include "gimple-fold.h"
#include "tree-ssa-loop-niter.h"
#include "internal-fn.h"
#include "stor-layout.h"
#include "optabs-query.h"
#include "vec-perm-indices.h"
#include "insn-config.h"
#include "rtl.h"
#include "recog.h"
#include "langhooks.h"
#include "tree-vector-builder.h"
#include "optabs-tree.h"

/*************************************************************************
  Simple Loop Peeling Utilities

  Utilities to support loop peeling for vectorization purposes.
 *************************************************************************/


/* Renames the use *OP_P.  */

static void
rename_use_op (use_operand_p op_p)
{
  tree new_name;

  if (TREE_CODE (USE_FROM_PTR (op_p)) != SSA_NAME)
    return;

  new_name = get_current_def (USE_FROM_PTR (op_p));

  /* Something defined outside of the loop.  */
  if (!new_name)
    return;

  /* An ordinary ssa name defined in the loop.  */

  SET_USE (op_p, new_name);
}


/* Renames the variables in basic block BB.  Allow renaming  of PHI arguments
   on edges incoming from outer-block header if RENAME_FROM_OUTER_LOOP is
   true.  */

static void
rename_variables_in_bb (basic_block bb, bool rename_from_outer_loop)
{
  gimple *stmt;
  use_operand_p use_p;
  ssa_op_iter iter;
  edge e;
  edge_iterator ei;
  class loop *loop = bb->loop_father;
  class loop *outer_loop = NULL;

  if (rename_from_outer_loop)
    {
      gcc_assert (loop);
      outer_loop = loop_outer (loop);
    }

  for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
       gsi_next (&gsi))
    {
      stmt = gsi_stmt (gsi);
      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
	rename_use_op (use_p);
    }

  FOR_EACH_EDGE (e, ei, bb->preds)
    {
      if (!flow_bb_inside_loop_p (loop, e->src))
	{
	  if (!rename_from_outer_loop)
	    continue;
	  if (e->src != outer_loop->header)
	    {
	      if (outer_loop->inner->next)
		{
		  /* If outer_loop has 2 inner loops, allow there to
		     be an extra basic block which decides which of the
		     two loops to use using LOOP_VECTORIZED.  */
		  if (!single_pred_p (e->src)
		      || single_pred (e->src) != outer_loop->header)
		    continue;
		}
	    }
	}
      for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
	   gsi_next (&gsi))
        rename_use_op (PHI_ARG_DEF_PTR_FROM_EDGE (gsi.phi (), e));
    }
}


struct adjust_info
{
  tree from, to;
  basic_block bb;
};

/* A stack of values to be adjusted in debug stmts.  We have to
   process them LIFO, so that the closest substitution applies.  If we
   processed them FIFO, without the stack, we might substitute uses
   with a PHI DEF that would soon become non-dominant, and when we got
   to the suitable one, it wouldn't have anything to substitute any
   more.  */
static vec<adjust_info, va_heap> adjust_vec;

/* Adjust any debug stmts that referenced AI->from values to use the
   loop-closed AI->to, if the references are dominated by AI->bb and
   not by the definition of AI->from.  */

static void
adjust_debug_stmts_now (adjust_info *ai)
{
  basic_block bbphi = ai->bb;
  tree orig_def = ai->from;
  tree new_def = ai->to;
  imm_use_iterator imm_iter;
  gimple *stmt;
  basic_block bbdef = gimple_bb (SSA_NAME_DEF_STMT (orig_def));

  gcc_assert (dom_info_available_p (CDI_DOMINATORS));

  /* Adjust any debug stmts that held onto non-loop-closed
     references.  */
  FOR_EACH_IMM_USE_STMT (stmt, imm_iter, orig_def)
    {
      use_operand_p use_p;
      basic_block bbuse;

      if (!is_gimple_debug (stmt))
	continue;

      gcc_assert (gimple_debug_bind_p (stmt));

      bbuse = gimple_bb (stmt);

      if ((bbuse == bbphi
	   || dominated_by_p (CDI_DOMINATORS, bbuse, bbphi))
	  && !(bbuse == bbdef
	       || dominated_by_p (CDI_DOMINATORS, bbuse, bbdef)))
	{
	  if (new_def)
	    FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
	      SET_USE (use_p, new_def);
	  else
	    {
	      gimple_debug_bind_reset_value (stmt);
	      update_stmt (stmt);
	    }
	}
    }
}

/* Adjust debug stmts as scheduled before.  */

static void
adjust_vec_debug_stmts (void)
{
  if (!MAY_HAVE_DEBUG_BIND_STMTS)
    return;

  gcc_assert (adjust_vec.exists ());

  while (!adjust_vec.is_empty ())
    {
      adjust_debug_stmts_now (&adjust_vec.last ());
      adjust_vec.pop ();
    }
}

/* Adjust any debug stmts that referenced FROM values to use the
   loop-closed TO, if the references are dominated by BB and not by
   the definition of FROM.  If adjust_vec is non-NULL, adjustments
   will be postponed until adjust_vec_debug_stmts is called.  */

static void
adjust_debug_stmts (tree from, tree to, basic_block bb)
{
  adjust_info ai;

  if (MAY_HAVE_DEBUG_BIND_STMTS
      && TREE_CODE (from) == SSA_NAME
      && ! SSA_NAME_IS_DEFAULT_DEF (from)
      && ! virtual_operand_p (from))
    {
      ai.from = from;
      ai.to = to;
      ai.bb = bb;

      if (adjust_vec.exists ())
	adjust_vec.safe_push (ai);
      else
	adjust_debug_stmts_now (&ai);
    }
}

/* Change E's phi arg in UPDATE_PHI to NEW_DEF, and record information
   to adjust any debug stmts that referenced the old phi arg,
   presumably non-loop-closed references left over from other
   transformations.  */

static void
adjust_phi_and_debug_stmts (gimple *update_phi, edge e, tree new_def)
{
  tree orig_def = PHI_ARG_DEF_FROM_EDGE (update_phi, e);

  gcc_assert (TREE_CODE (orig_def) != SSA_NAME
	      || orig_def != new_def);

  SET_PHI_ARG_DEF (update_phi, e->dest_idx, new_def);

  if (MAY_HAVE_DEBUG_BIND_STMTS)
    adjust_debug_stmts (orig_def, PHI_RESULT (update_phi),
			gimple_bb (update_phi));
}

/* Define one loop rgroup control CTRL from loop LOOP.  INIT_CTRL is the value
   that the control should have during the first iteration and NEXT_CTRL is the
   value that it should have on subsequent iterations.  */

static void
vect_set_loop_control (class loop *loop, tree ctrl, tree init_ctrl,
		       tree next_ctrl)
{
  gphi *phi = create_phi_node (ctrl, loop->header);
  add_phi_arg (phi, init_ctrl, loop_preheader_edge (loop), UNKNOWN_LOCATION);
  add_phi_arg (phi, next_ctrl, loop_latch_edge (loop), UNKNOWN_LOCATION);
}

/* Add SEQ to the end of LOOP's preheader block.  */

static void
add_preheader_seq (class loop *loop, gimple_seq seq)
{
  if (seq)
    {
      edge pe = loop_preheader_edge (loop);
      basic_block new_bb = gsi_insert_seq_on_edge_immediate (pe, seq);
      gcc_assert (!new_bb);
    }
}

/* Add SEQ to the beginning of LOOP's header block.  */

static void
add_header_seq (class loop *loop, gimple_seq seq)
{
  if (seq)
    {
      gimple_stmt_iterator gsi = gsi_after_labels (loop->header);
      gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
    }
}

/* Return true if the target can interleave elements of two vectors.
   OFFSET is 0 if the first half of the vectors should be interleaved
   or 1 if the second half should.  When returning true, store the
   associated permutation in INDICES.  */

static bool
interleave_supported_p (vec_perm_indices *indices, tree vectype,
			unsigned int offset)
{
  poly_uint64 nelts = TYPE_VECTOR_SUBPARTS (vectype);
  poly_uint64 base = exact_div (nelts, 2) * offset;
  vec_perm_builder sel (nelts, 2, 3);
  for (unsigned int i = 0; i < 3; ++i)
    {
      sel.quick_push (base + i);
      sel.quick_push (base + i + nelts);
    }
  indices->new_vector (sel, 2, nelts);
  return can_vec_perm_const_p (TYPE_MODE (vectype), TYPE_MODE (vectype),
			       *indices);
}

/* Try to use permutes to define the masks in DEST_RGM using the masks
   in SRC_RGM, given that the former has twice as many masks as the
   latter.  Return true on success, adding any new statements to SEQ.  */

static bool
vect_maybe_permute_loop_masks (gimple_seq *seq, rgroup_controls *dest_rgm,
			       rgroup_controls *src_rgm)
{
  tree src_masktype = src_rgm->type;
  tree dest_masktype = dest_rgm->type;
  machine_mode src_mode = TYPE_MODE (src_masktype);
  insn_code icode1, icode2;
  if (dest_rgm->max_nscalars_per_iter <= src_rgm->max_nscalars_per_iter
      && (icode1 = optab_handler (vec_unpacku_hi_optab,
				  src_mode)) != CODE_FOR_nothing
      && (icode2 = optab_handler (vec_unpacku_lo_optab,
				  src_mode)) != CODE_FOR_nothing)
    {
      /* Unpacking the source masks gives at least as many mask bits as
	 we need.  We can then VIEW_CONVERT any excess bits away.  */
      machine_mode dest_mode = insn_data[icode1].operand[0].mode;
      gcc_assert (dest_mode == insn_data[icode2].operand[0].mode);
      tree unpack_masktype = vect_halve_mask_nunits (src_masktype, dest_mode);
      for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i)
	{
	  tree src = src_rgm->controls[i / 2];
	  tree dest = dest_rgm->controls[i];
	  tree_code code = ((i & 1) == (BYTES_BIG_ENDIAN ? 0 : 1)
			    ? VEC_UNPACK_HI_EXPR
			    : VEC_UNPACK_LO_EXPR);
	  gassign *stmt;
	  if (dest_masktype == unpack_masktype)
	    stmt = gimple_build_assign (dest, code, src);
	  else
	    {
	      tree temp = make_ssa_name (unpack_masktype);
	      stmt = gimple_build_assign (temp, code, src);
	      gimple_seq_add_stmt (seq, stmt);
	      stmt = gimple_build_assign (dest, VIEW_CONVERT_EXPR,
					  build1 (VIEW_CONVERT_EXPR,
						  dest_masktype, temp));
	    }
	  gimple_seq_add_stmt (seq, stmt);
	}
      return true;
    }
  vec_perm_indices indices[2];
  if (dest_masktype == src_masktype
      && interleave_supported_p (&indices[0], src_masktype, 0)
      && interleave_supported_p (&indices[1], src_masktype, 1))
    {
      /* The destination requires twice as many mask bits as the source, so
	 we can use interleaving permutes to double up the number of bits.  */
      tree masks[2];
      for (unsigned int i = 0; i < 2; ++i)
	masks[i] = vect_gen_perm_mask_checked (src_masktype, indices[i]);
      for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i)
	{
	  tree src = src_rgm->controls[i / 2];
	  tree dest = dest_rgm->controls[i];
	  gimple *stmt = gimple_build_assign (dest, VEC_PERM_EXPR,
					      src, src, masks[i & 1]);
	  gimple_seq_add_stmt (seq, stmt);
	}
      return true;
    }
  return false;
}

/* Populate DEST_RGM->controls, given that they should add up to STEP.

     STEP = MIN_EXPR <ivtmp_34, VF>;

     First length (MIN (X, VF/N)):
       loop_len_15 = MIN_EXPR <STEP, VF/N>;

     Second length:
       tmp = STEP - loop_len_15;
       loop_len_16 = MIN (tmp, VF/N);

     Third length:
       tmp2 = tmp - loop_len_16;
       loop_len_17 = MIN (tmp2, VF/N);

     Last length:
       loop_len_18 = tmp2 - loop_len_17;
*/

static void
vect_adjust_loop_lens_control (tree iv_type, gimple_seq *seq,
			       rgroup_controls *dest_rgm, tree step)
{
  tree ctrl_type = dest_rgm->type;
  poly_uint64 nitems_per_ctrl
    = TYPE_VECTOR_SUBPARTS (ctrl_type) * dest_rgm->factor;
  tree length_limit = build_int_cst (iv_type, nitems_per_ctrl);

  for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i)
    {
      tree ctrl = dest_rgm->controls[i];
      if (i == 0)
	{
	  /* First iteration: MIN (X, VF/N) capped to the range [0, VF/N].  */
	  gassign *assign
	    = gimple_build_assign (ctrl, MIN_EXPR, step, length_limit);
	  gimple_seq_add_stmt (seq, assign);
	}
      else if (i == dest_rgm->controls.length () - 1)
	{
	  /* Last iteration: Remain capped to the range [0, VF/N].  */
	  gassign *assign = gimple_build_assign (ctrl, MINUS_EXPR, step,
						 dest_rgm->controls[i - 1]);
	  gimple_seq_add_stmt (seq, assign);
	}
      else
	{
	  /* (MIN (remain, VF*I/N)) capped to the range [0, VF/N].  */
	  step = gimple_build (seq, MINUS_EXPR, iv_type, step,
			       dest_rgm->controls[i - 1]);
	  gassign *assign
	    = gimple_build_assign (ctrl, MIN_EXPR, step, length_limit);
	  gimple_seq_add_stmt (seq, assign);
	}
    }
}

/* Stores the standard position for induction variable increment in belonging to
   LOOP_EXIT (just before the exit condition of the given exit to BSI.
   INSERT_AFTER is set to true if the increment should be inserted after
   *BSI.  */

void
vect_iv_increment_position (edge loop_exit, gimple_stmt_iterator *bsi,
			    bool *insert_after)
{
  basic_block bb = loop_exit->src;
  *bsi = gsi_last_bb (bb);
  *insert_after = false;
}

/* Helper for vect_set_loop_condition_partial_vectors.  Generate definitions
   for all the rgroup controls in RGC and return a control that is nonzero
   when the loop needs to iterate.  Add any new preheader statements to
   PREHEADER_SEQ.  Use LOOP_COND_GSI to insert code before the exit gcond.

   RGC belongs to loop LOOP.  The loop originally iterated NITERS
   times and has been vectorized according to LOOP_VINFO.

   If NITERS_SKIP is nonnull, the first iteration of the vectorized loop
   starts with NITERS_SKIP dummy iterations of the scalar loop before
   the real work starts.  The mask elements for these dummy iterations
   must be 0, to ensure that the extra iterations do not have an effect.

   It is known that:

     NITERS * RGC->max_nscalars_per_iter * RGC->factor

   does not overflow.  However, MIGHT_WRAP_P says whether an induction
   variable that starts at 0 and has step:

     VF * RGC->max_nscalars_per_iter * RGC->factor

   might overflow before hitting a value above:

     (NITERS + NITERS_SKIP) * RGC->max_nscalars_per_iter * RGC->factor

   This means that we cannot guarantee that such an induction variable
   would ever hit a value that produces a set of all-false masks or zero
   lengths for RGC.

   Note: the cost of the code generated by this function is modeled
   by vect_estimate_min_profitable_iters, so changes here may need
   corresponding changes there.  */

static tree
vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
				 gimple_seq *preheader_seq,
				 gimple_seq *header_seq,
				 gimple_stmt_iterator loop_cond_gsi,
				 rgroup_controls *rgc, tree niters,
				 tree niters_skip, bool might_wrap_p,
				 tree *iv_step, tree *compare_step)
{
  tree compare_type = LOOP_VINFO_RGROUP_COMPARE_TYPE (loop_vinfo);
  tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
  bool use_masks_p = LOOP_VINFO_FULLY_MASKED_P (loop_vinfo);

  tree ctrl_type = rgc->type;
  unsigned int nitems_per_iter = rgc->max_nscalars_per_iter * rgc->factor;
  poly_uint64 nitems_per_ctrl = TYPE_VECTOR_SUBPARTS (ctrl_type) * rgc->factor;
  poly_uint64 vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
  tree length_limit = NULL_TREE;
  /* For length, we need length_limit to ensure length in range.  */
  if (!use_masks_p)
    length_limit = build_int_cst (compare_type, nitems_per_ctrl);

  /* Calculate the maximum number of item values that the rgroup
     handles in total, the number that it handles for each iteration
     of the vector loop, and the number that it should skip during the
     first iteration of the vector loop.  */
  tree nitems_total = niters;
  tree nitems_step = build_int_cst (iv_type, vf);
  tree nitems_skip = niters_skip;
  if (nitems_per_iter != 1)
    {
      /* We checked before setting LOOP_VINFO_USING_PARTIAL_VECTORS_P that
	 these multiplications don't overflow.  */
      tree compare_factor = build_int_cst (compare_type, nitems_per_iter);
      tree iv_factor = build_int_cst (iv_type, nitems_per_iter);
      nitems_total = gimple_build (preheader_seq, MULT_EXPR, compare_type,
				   nitems_total, compare_factor);
      nitems_step = gimple_build (preheader_seq, MULT_EXPR, iv_type,
				  nitems_step, iv_factor);
      if (nitems_skip)
	nitems_skip = gimple_build (preheader_seq, MULT_EXPR, compare_type,
				    nitems_skip, compare_factor);
    }

  /* Create an induction variable that counts the number of items
     processed.  */
  tree index_before_incr, index_after_incr;
  gimple_stmt_iterator incr_gsi;
  bool insert_after;
  edge exit_e = LOOP_VINFO_IV_EXIT (loop_vinfo);
  vect_iv_increment_position (exit_e, &incr_gsi, &insert_after);
  if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo))
    {
      /* Create an IV that counts down from niters_total and whose step
	 is the (variable) amount processed in the current iteration:
	   ...
	   _10 = (unsigned long) count_12(D);
	   ...
	   # ivtmp_9 = PHI <ivtmp_35(6), _10(5)>
	   _36 = (MIN_EXPR | SELECT_VL) <ivtmp_9, POLY_INT_CST [4, 4]>;
	   ...
	   vect__4.8_28 = .LEN_LOAD (_17, 32B, _36, 0);
	   ...
	   ivtmp_35 = ivtmp_9 - POLY_INT_CST [4, 4];
	   ...
	   if (ivtmp_9 > POLY_INT_CST [4, 4])
	     goto <bb 4>; [83.33%]
	   else
	     goto <bb 5>; [16.67%]
      */
      nitems_total = gimple_convert (preheader_seq, iv_type, nitems_total);
      tree step = rgc->controls.length () == 1 ? rgc->controls[0]
					       : make_ssa_name (iv_type);
      /* Create decrement IV.  */
      if (LOOP_VINFO_USING_SELECT_VL_P (loop_vinfo))
	{
	  create_iv (nitems_total, MINUS_EXPR, step, NULL_TREE, loop, &incr_gsi,
		     insert_after, &index_before_incr, &index_after_incr);
	  tree len = gimple_build (header_seq, IFN_SELECT_VL, iv_type,
				   index_before_incr, nitems_step);
	  gimple_seq_add_stmt (header_seq, gimple_build_assign (step, len));
	}
      else
	{
	  create_iv (nitems_total, MINUS_EXPR, nitems_step, NULL_TREE, loop,
		     &incr_gsi, insert_after, &index_before_incr,
		     &index_after_incr);
	  gimple_seq_add_stmt (header_seq,
			       gimple_build_assign (step, MIN_EXPR,
						    index_before_incr,
						    nitems_step));
	}
      *iv_step = step;
      *compare_step = nitems_step;
      return LOOP_VINFO_USING_SELECT_VL_P (loop_vinfo) ? index_after_incr
						       : index_before_incr;
    }

  /* Create increment IV.  */
  create_iv (build_int_cst (iv_type, 0), PLUS_EXPR, nitems_step, NULL_TREE,
	     loop, &incr_gsi, insert_after, &index_before_incr,
	     &index_after_incr);

  tree zero_index = build_int_cst (compare_type, 0);
  tree test_index, test_limit, first_limit;
  gimple_stmt_iterator *test_gsi;
  if (might_wrap_p)
    {
      /* In principle the loop should stop iterating once the incremented
	 IV reaches a value greater than or equal to:

	   NITEMS_TOTAL +[infinite-prec] NITEMS_SKIP

	 However, there's no guarantee that this addition doesn't overflow
	 the comparison type, or that the IV hits a value above it before
	 wrapping around.  We therefore adjust the limit down by one
	 IV step:

	   (NITEMS_TOTAL +[infinite-prec] NITEMS_SKIP)
	   -[infinite-prec] NITEMS_STEP

	 and compare the IV against this limit _before_ incrementing it.
	 Since the comparison type is unsigned, we actually want the
	 subtraction to saturate at zero:

	   (NITEMS_TOTAL +[infinite-prec] NITEMS_SKIP)
	   -[sat] NITEMS_STEP

	 And since NITEMS_SKIP < NITEMS_STEP, we can reassociate this as:

	   NITEMS_TOTAL -[sat] (NITEMS_STEP - NITEMS_SKIP)

	 where the rightmost subtraction can be done directly in
	 COMPARE_TYPE.  */
      test_index = index_before_incr;
      tree adjust = gimple_convert (preheader_seq, compare_type,
				    nitems_step);
      if (nitems_skip)
	adjust = gimple_build (preheader_seq, MINUS_EXPR, compare_type,
			       adjust, nitems_skip);
      test_limit = gimple_build (preheader_seq, MAX_EXPR, compare_type,
				 nitems_total, adjust);
      test_limit = gimple_build (preheader_seq, MINUS_EXPR, compare_type,
				 test_limit, adjust);
      test_gsi = &incr_gsi;

      /* Get a safe limit for the first iteration.  */
      if (nitems_skip)
	{
	  /* The first vector iteration can handle at most NITEMS_STEP
	     items.  NITEMS_STEP <= CONST_LIMIT, and adding
	     NITEMS_SKIP to that cannot overflow.  */
	  tree const_limit = build_int_cst (compare_type,
					    LOOP_VINFO_VECT_FACTOR (loop_vinfo)
					    * nitems_per_iter);
	  first_limit = gimple_build (preheader_seq, MIN_EXPR, compare_type,
				      nitems_total, const_limit);
	  first_limit = gimple_build (preheader_seq, PLUS_EXPR, compare_type,
				      first_limit, nitems_skip);
	}
      else
	/* For the first iteration it doesn't matter whether the IV hits
	   a value above NITEMS_TOTAL.  That only matters for the latch
	   condition.  */
	first_limit = nitems_total;
    }
  else
    {
      /* Test the incremented IV, which will always hit a value above
	 the bound before wrapping.  */
      test_index = index_after_incr;
      test_limit = nitems_total;
      if (nitems_skip)
	test_limit = gimple_build (preheader_seq, PLUS_EXPR, compare_type,
				   test_limit, nitems_skip);
      test_gsi = &loop_cond_gsi;

      first_limit = test_limit;
    }

  /* Convert the IV value to the comparison type (either a no-op or
     a demotion).  */
  gimple_seq test_seq = NULL;
  test_index = gimple_convert (&test_seq, compare_type, test_index);
  gsi_insert_seq_before (test_gsi, test_seq, GSI_SAME_STMT);

  /* Provide a definition of each control in the group.  */
  tree next_ctrl = NULL_TREE;
  tree ctrl;
  unsigned int i;
  FOR_EACH_VEC_ELT_REVERSE (rgc->controls, i, ctrl)
    {
      /* Previous controls will cover BIAS items.  This control covers the
	 next batch.  */
      poly_uint64 bias = nitems_per_ctrl * i;
      tree bias_tree = build_int_cst (compare_type, bias);

      /* See whether the first iteration of the vector loop is known
	 to have a full control.  */
      poly_uint64 const_limit;
      bool first_iteration_full
	= (poly_int_tree_p (first_limit, &const_limit)
	   && known_ge (const_limit, (i + 1) * nitems_per_ctrl));

      /* Rather than have a new IV that starts at BIAS and goes up to
	 TEST_LIMIT, prefer to use the same 0-based IV for each control
	 and adjust the bound down by BIAS.  */
      tree this_test_limit = test_limit;
      if (i != 0)
	{
	  this_test_limit = gimple_build (preheader_seq, MAX_EXPR,
					  compare_type, this_test_limit,
					  bias_tree);
	  this_test_limit = gimple_build (preheader_seq, MINUS_EXPR,
					  compare_type, this_test_limit,
					  bias_tree);
	}

      /* Create the initial control.  First include all items that
	 are within the loop limit.  */
      tree init_ctrl = NULL_TREE;
      if (!first_iteration_full)
	{
	  tree start, end;
	  if (first_limit == test_limit)
	    {
	      /* Use a natural test between zero (the initial IV value)
		 and the loop limit.  The "else" block would be valid too,
		 but this choice can avoid the need to load BIAS_TREE into
		 a register.  */
	      start = zero_index;
	      end = this_test_limit;
	    }
	  else
	    {
	      /* FIRST_LIMIT is the maximum number of items handled by the
		 first iteration of the vector loop.  Test the portion
		 associated with this control.  */
	      start = bias_tree;
	      end = first_limit;
	    }

	  if (use_masks_p)
	    init_ctrl = vect_gen_while (preheader_seq, ctrl_type,
					start, end, "max_mask");
	  else
	    {
	      init_ctrl = make_temp_ssa_name (compare_type, NULL, "max_len");
	      gimple_seq seq = vect_gen_len (init_ctrl, start,
					     end, length_limit);
	      gimple_seq_add_seq (preheader_seq, seq);
	    }
	}

      /* Now AND out the bits that are within the number of skipped
	 items.  */
      poly_uint64 const_skip;
      if (nitems_skip
	  && !(poly_int_tree_p (nitems_skip, &const_skip)
	       && known_le (const_skip, bias)))
	{
	  gcc_assert (use_masks_p);
	  tree unskipped_mask = vect_gen_while_not (preheader_seq, ctrl_type,
						    bias_tree, nitems_skip);
	  if (init_ctrl)
	    init_ctrl = gimple_build (preheader_seq, BIT_AND_EXPR, ctrl_type,
				      init_ctrl, unskipped_mask);
	  else
	    init_ctrl = unskipped_mask;
	}

      if (!init_ctrl)
	{
	  /* First iteration is full.  */
	  if (use_masks_p)
	    init_ctrl = build_minus_one_cst (ctrl_type);
	  else
	    init_ctrl = length_limit;
	}

      /* Get the control value for the next iteration of the loop.  */
      if (use_masks_p)
	{
	  gimple_seq stmts = NULL;
	  next_ctrl = vect_gen_while (&stmts, ctrl_type, test_index,
				      this_test_limit, "next_mask");
	  gsi_insert_seq_before (test_gsi, stmts, GSI_SAME_STMT);
	}
      else
	{
	  next_ctrl = make_temp_ssa_name (compare_type, NULL, "next_len");
	  gimple_seq seq = vect_gen_len (next_ctrl, test_index, this_test_limit,
					 length_limit);
	  gsi_insert_seq_before (test_gsi, seq, GSI_SAME_STMT);
	}

      vect_set_loop_control (loop, ctrl, init_ctrl, next_ctrl);
    }

  int partial_load_bias = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
  if (partial_load_bias != 0)
    {
      tree adjusted_len = rgc->bias_adjusted_ctrl;
      gassign *minus = gimple_build_assign (adjusted_len, PLUS_EXPR,
					    rgc->controls[0],
					    build_int_cst
					    (TREE_TYPE (rgc->controls[0]),
					     partial_load_bias));
      gimple_seq_add_stmt (header_seq, minus);
    }

  return next_ctrl;
}

/* Set up the iteration condition and rgroup controls for LOOP, given
   that LOOP_VINFO_USING_PARTIAL_VECTORS_P is true for the vectorized
   loop.  LOOP_VINFO describes the vectorization of LOOP.  NITERS is
   the number of iterations of the original scalar loop that should be
   handled by the vector loop.  NITERS_MAYBE_ZERO and FINAL_IV are as
   for vect_set_loop_condition.

   Insert the branch-back condition before LOOP_COND_GSI and return the
   final gcond.  */

static gcond *
vect_set_loop_condition_partial_vectors (class loop *loop, edge exit_edge,
					 loop_vec_info loop_vinfo, tree niters,
					 tree final_iv, bool niters_maybe_zero,
					 gimple_stmt_iterator loop_cond_gsi)
{
  gimple_seq preheader_seq = NULL;
  gimple_seq header_seq = NULL;

  bool use_masks_p = LOOP_VINFO_FULLY_MASKED_P (loop_vinfo);
  tree compare_type = LOOP_VINFO_RGROUP_COMPARE_TYPE (loop_vinfo);
  unsigned int compare_precision = TYPE_PRECISION (compare_type);
  tree orig_niters = niters;

  /* Type of the initial value of NITERS.  */
  tree ni_actual_type = TREE_TYPE (niters);
  unsigned int ni_actual_precision = TYPE_PRECISION (ni_actual_type);
  tree niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
  if (niters_skip)
    niters_skip = gimple_convert (&preheader_seq, compare_type, niters_skip);

  /* Convert NITERS to the same size as the compare.  */
  if (compare_precision > ni_actual_precision
      && niters_maybe_zero)
    {
      /* We know that there is always at least one iteration, so if the
	 count is zero then it must have wrapped.  Cope with this by
	 subtracting 1 before the conversion and adding 1 to the result.  */
      gcc_assert (TYPE_UNSIGNED (ni_actual_type));
      niters = gimple_build (&preheader_seq, PLUS_EXPR, ni_actual_type,
			     niters, build_minus_one_cst (ni_actual_type));
      niters = gimple_convert (&preheader_seq, compare_type, niters);
      niters = gimple_build (&preheader_seq, PLUS_EXPR, compare_type,
			     niters, build_one_cst (compare_type));
    }
  else
    niters = gimple_convert (&preheader_seq, compare_type, niters);

  /* Iterate over all the rgroups and fill in their controls.  We could use
     the first control from any rgroup for the loop condition; here we
     arbitrarily pick the last.  */
  tree test_ctrl = NULL_TREE;
  tree iv_step = NULL_TREE;
  tree compare_step = NULL_TREE;
  rgroup_controls *rgc;
  rgroup_controls *iv_rgc = nullptr;
  unsigned int i;
  auto_vec<rgroup_controls> *controls = use_masks_p
					  ? &LOOP_VINFO_MASKS (loop_vinfo).rgc_vec
					  : &LOOP_VINFO_LENS (loop_vinfo);
  FOR_EACH_VEC_ELT (*controls, i, rgc)
    if (!rgc->controls.is_empty ())
      {
	/* First try using permutes.  This adds a single vector
	   instruction to the loop for each mask, but needs no extra
	   loop invariants or IVs.  */
	unsigned int nmasks = i + 1;
	if (use_masks_p && (nmasks & 1) == 0)
	  {
	    rgroup_controls *half_rgc = &(*controls)[nmasks / 2 - 1];
	    if (!half_rgc->controls.is_empty ()
		&& vect_maybe_permute_loop_masks (&header_seq, rgc, half_rgc))
	      continue;
	  }

	if (!LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo)
	    || !iv_rgc
	    || (iv_rgc->max_nscalars_per_iter * iv_rgc->factor
		!= rgc->max_nscalars_per_iter * rgc->factor))
	  {
	    /* See whether zero-based IV would ever generate all-false masks
	       or zero length before wrapping around.  */
	    bool might_wrap_p = vect_rgroup_iv_might_wrap_p (loop_vinfo, rgc);

	    /* Set up all controls for this group.  */
	    test_ctrl
	      = vect_set_loop_controls_directly (loop, loop_vinfo,
						 &preheader_seq, &header_seq,
						 loop_cond_gsi, rgc, niters,
						 niters_skip, might_wrap_p,
						 &iv_step, &compare_step);

	    iv_rgc = rgc;
	  }

	if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo)
	    && rgc->controls.length () > 1)
	  {
	    /* vect_set_loop_controls_directly creates an IV whose step
	       is equal to the expected sum of RGC->controls.  Use that
	       information to populate RGC->controls.  */
	    tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
	    gcc_assert (iv_step);
	    vect_adjust_loop_lens_control (iv_type, &header_seq, rgc, iv_step);
	  }
      }

  /* Emit all accumulated statements.  */
  add_preheader_seq (loop, preheader_seq);
  add_header_seq (loop, header_seq);

  /* Get a boolean result that tells us whether to iterate.  */
  gcond *cond_stmt;
  if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo)
      && !LOOP_VINFO_USING_SELECT_VL_P (loop_vinfo))
    {
      gcc_assert (compare_step);
      tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? LE_EXPR : GT_EXPR;
      cond_stmt = gimple_build_cond (code, test_ctrl, compare_step, NULL_TREE,
				     NULL_TREE);
    }
  else
    {
      tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? EQ_EXPR : NE_EXPR;
      tree zero_ctrl = build_zero_cst (TREE_TYPE (test_ctrl));
      cond_stmt
	= gimple_build_cond (code, test_ctrl, zero_ctrl, NULL_TREE, NULL_TREE);
    }
  gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);

  /* The loop iterates (NITERS - 1) / VF + 1 times.
     Subtract one from this to get the latch count.  */
  tree step = build_int_cst (compare_type,
			     LOOP_VINFO_VECT_FACTOR (loop_vinfo));
  tree niters_minus_one = fold_build2 (PLUS_EXPR, compare_type, niters,
				       build_minus_one_cst (compare_type));
  loop->nb_iterations = fold_build2 (TRUNC_DIV_EXPR, compare_type,
				     niters_minus_one, step);

  if (final_iv)
    {
      gassign *assign;
      /* If vectorizing an inverted early break loop we have to restart the
	 scalar loop at niters - vf.  This matches what we do in
	 vect_gen_vector_loop_niters_mult_vf for non-masked loops.  */
      if (LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo))
	{
	  tree ftype = TREE_TYPE (orig_niters);
	  tree vf = build_int_cst (ftype, LOOP_VINFO_VECT_FACTOR (loop_vinfo));
	  assign = gimple_build_assign (final_iv, MINUS_EXPR, orig_niters, vf);
	}
       else
	assign = gimple_build_assign (final_iv, orig_niters);
      gsi_insert_on_edge_immediate (exit_edge, assign);
    }

  return cond_stmt;
}

/* Set up the iteration condition and rgroup controls for LOOP in AVX512
   style, given that LOOP_VINFO_USING_PARTIAL_VECTORS_P is true for the
   vectorized loop.  LOOP_VINFO describes the vectorization of LOOP.  NITERS is
   the number of iterations of the original scalar loop that should be
   handled by the vector loop.  NITERS_MAYBE_ZERO and FINAL_IV are as
   for vect_set_loop_condition.

   Insert the branch-back condition before LOOP_COND_GSI and return the
   final gcond.  */

static gcond *
vect_set_loop_condition_partial_vectors_avx512 (class loop *loop,
					 edge exit_edge,
					 loop_vec_info loop_vinfo, tree niters,
					 tree final_iv,
					 bool niters_maybe_zero,
					 gimple_stmt_iterator loop_cond_gsi)
{
  tree niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
  tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
  poly_uint64 vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
  tree orig_niters = niters;
  gimple_seq preheader_seq = NULL;

  /* Create an IV that counts down from niters and whose step
     is the number of iterations processed in the current iteration.
     Produce the controls with compares like the following.

       # iv_2 = PHI <niters, iv_3>
       rem_4 = MIN <iv_2, VF>;
       remv_6 = { rem_4, rem_4, rem_4, ... }
       mask_5 = { 0, 0, 1, 1, 2, 2, ... } < remv6;
       iv_3 = iv_2 - VF;
       if (iv_2 > VF)
	 continue;

     Where the constant is built with elements at most VF - 1 and
     repetitions according to max_nscalars_per_iter which is guarnateed
     to be the same within a group.  */

  /* Convert NITERS to the determined IV type.  */
  if (TYPE_PRECISION (iv_type) > TYPE_PRECISION (TREE_TYPE (niters))
      && niters_maybe_zero)
    {
      /* We know that there is always at least one iteration, so if the
	 count is zero then it must have wrapped.  Cope with this by
	 subtracting 1 before the conversion and adding 1 to the result.  */
      gcc_assert (TYPE_UNSIGNED (TREE_TYPE (niters)));
      niters = gimple_build (&preheader_seq, PLUS_EXPR, TREE_TYPE (niters),
			     niters, build_minus_one_cst (TREE_TYPE (niters)));
      niters = gimple_convert (&preheader_seq, iv_type, niters);
      niters = gimple_build (&preheader_seq, PLUS_EXPR, iv_type,
			     niters, build_one_cst (iv_type));
    }
  else
    niters = gimple_convert (&preheader_seq, iv_type, niters);

  /* Bias the initial value of the IV in case we need to skip iterations
     at the beginning.  */
  tree niters_adj = niters;
  if (niters_skip)
    {
      tree skip = gimple_convert (&preheader_seq, iv_type, niters_skip);
      niters_adj = gimple_build (&preheader_seq, PLUS_EXPR,
				 iv_type, niters, skip);
    }

  /* The iteration step is the vectorization factor.  */
  tree iv_step = build_int_cst (iv_type, vf);

  /* Create the decrement IV.  */
  tree index_before_incr, index_after_incr;
  gimple_stmt_iterator incr_gsi;
  bool insert_after;
  vect_iv_increment_position (exit_edge, &incr_gsi, &insert_after);
  create_iv (niters_adj, MINUS_EXPR, iv_step, NULL_TREE, loop,
	     &incr_gsi, insert_after, &index_before_incr,
	     &index_after_incr);

  /* Iterate over all the rgroups and fill in their controls.  */
  for (auto &rgc : LOOP_VINFO_MASKS (loop_vinfo).rgc_vec)
    {
      if (rgc.controls.is_empty ())
	continue;

      tree ctrl_type = rgc.type;
      poly_uint64 nitems_per_ctrl = TYPE_VECTOR_SUBPARTS (ctrl_type);

      tree vectype = rgc.compare_type;

      /* index_after_incr is the IV specifying the remaining iterations in
	 the next iteration.  */
      tree rem = index_after_incr;
      /* When the data type for the compare to produce the mask is
	 smaller than the IV type we need to saturate.  Saturate to
	 the smallest possible value (IV_TYPE) so we only have to
	 saturate once (CSE will catch redundant ones we add).  */
      if (TYPE_PRECISION (TREE_TYPE (vectype)) < TYPE_PRECISION (iv_type))
	rem = gimple_build (&incr_gsi, false, GSI_CONTINUE_LINKING,
			    UNKNOWN_LOCATION,
			    MIN_EXPR, TREE_TYPE (rem), rem, iv_step);
      rem = gimple_convert (&incr_gsi, false, GSI_CONTINUE_LINKING,
			    UNKNOWN_LOCATION, TREE_TYPE (vectype), rem);

      /* Build a data vector composed of the remaining iterations.  */
      rem = gimple_build_vector_from_val (&incr_gsi, false, GSI_CONTINUE_LINKING,
					  UNKNOWN_LOCATION, vectype, rem);

      /* Provide a definition of each vector in the control group.  */
      tree next_ctrl = NULL_TREE;
      tree first_rem = NULL_TREE;
      tree ctrl;
      unsigned int i;
      FOR_EACH_VEC_ELT_REVERSE (rgc.controls, i, ctrl)
	{
	  /* Previous controls will cover BIAS items.  This control covers the
	     next batch.  */
	  poly_uint64 bias = nitems_per_ctrl * i;

	  /* Build the constant to compare the remaining iters against,
	     this is sth like { 0, 0, 1, 1, 2, 2, 3, 3, ... } appropriately
	     split into pieces.  */
	  unsigned n = TYPE_VECTOR_SUBPARTS (ctrl_type).to_constant ();
	  tree_vector_builder builder (vectype, n, 1);
	  for (unsigned i = 0; i < n; ++i)
	    {
	      unsigned HOST_WIDE_INT val
		= (i + bias.to_constant ()) / rgc.max_nscalars_per_iter;
	      gcc_assert (val < vf.to_constant ());
	      builder.quick_push (build_int_cst (TREE_TYPE (vectype), val));
	    }
	  tree cmp_series = builder.build ();

	  /* Create the initial control.  First include all items that
	     are within the loop limit.  */
	  tree init_ctrl = NULL_TREE;
	  poly_uint64 const_limit;
	  /* See whether the first iteration of the vector loop is known
	     to have a full control.  */
	  if (poly_int_tree_p (niters, &const_limit)
	      && known_ge (const_limit, (i + 1) * nitems_per_ctrl))
	    init_ctrl = build_minus_one_cst (ctrl_type);
	  else
	    {
	      /* The remaining work items initially are niters.  Saturate,
		 splat and compare.  */
	      if (!first_rem)
		{
		  first_rem = niters;
		  if (TYPE_PRECISION (TREE_TYPE (vectype))
		      < TYPE_PRECISION (iv_type))
		    first_rem = gimple_build (&preheader_seq,
					      MIN_EXPR, TREE_TYPE (first_rem),
					      first_rem, iv_step);
		  first_rem = gimple_convert (&preheader_seq, TREE_TYPE (vectype),
					      first_rem);
		  first_rem = gimple_build_vector_from_val (&preheader_seq,
							    vectype, first_rem);
		}
	      init_ctrl = gimple_build (&preheader_seq, LT_EXPR, ctrl_type,
					cmp_series, first_rem);
	    }

	  /* Now AND out the bits that are within the number of skipped
	     items.  */
	  poly_uint64 const_skip;
	  if (niters_skip
	      && !(poly_int_tree_p (niters_skip, &const_skip)
		   && known_le (const_skip, bias)))
	    {
	      /* For integer mode masks it's cheaper to shift out the bits
		 since that avoids loading a constant.  */
	      gcc_assert (GET_MODE_CLASS (TYPE_MODE (ctrl_type)) == MODE_INT);
	      init_ctrl = gimple_build (&preheader_seq, VIEW_CONVERT_EXPR,
					lang_hooks.types.type_for_mode
					  (TYPE_MODE (ctrl_type), 1),
					init_ctrl);
	      /* ???  But when the shift amount isn't constant this requires
		 a round-trip to GRPs.  We could apply the bias to either
		 side of the compare instead.  */
	      tree shift = gimple_build (&preheader_seq, MULT_EXPR,
					 TREE_TYPE (niters_skip), niters_skip,
					 build_int_cst (TREE_TYPE (niters_skip),
							rgc.max_nscalars_per_iter));
	      init_ctrl = gimple_build (&preheader_seq, LSHIFT_EXPR,
					TREE_TYPE (init_ctrl),
					init_ctrl, shift);
	      init_ctrl = gimple_build (&preheader_seq, VIEW_CONVERT_EXPR,
					ctrl_type, init_ctrl);
	    }

	  /* Get the control value for the next iteration of the loop.  */
	  next_ctrl = gimple_build (&incr_gsi, false, GSI_CONTINUE_LINKING,
				    UNKNOWN_LOCATION,
				    LT_EXPR, ctrl_type, cmp_series, rem);

	  vect_set_loop_control (loop, ctrl, init_ctrl, next_ctrl);
	}
    }

  /* Emit all accumulated statements.  */
  add_preheader_seq (loop, preheader_seq);

  /* Adjust the exit test using the decrementing IV.  */
  tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? LE_EXPR : GT_EXPR;
  /* When we peel for alignment with niter_skip != 0 this can
     cause niter + niter_skip to wrap and since we are comparing the
     value before the decrement here we get a false early exit.
     We can't compare the value after decrement either because that
     decrement could wrap as well as we're not doing a saturating
     decrement.  To avoid this situation we force a larger
     iv_type.  */
  gcond *cond_stmt = gimple_build_cond (code, index_before_incr, iv_step,
					NULL_TREE, NULL_TREE);
  gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);

  /* The loop iterates (NITERS - 1 + NITERS_SKIP) / VF + 1 times.
     Subtract one from this to get the latch count.  */
  tree niters_minus_one
    = fold_build2 (PLUS_EXPR, TREE_TYPE (orig_niters), orig_niters,
		   build_minus_one_cst (TREE_TYPE (orig_niters)));
  tree niters_adj2 = fold_convert (iv_type, niters_minus_one);
  if (niters_skip)
    niters_adj2 = fold_build2 (PLUS_EXPR, iv_type, niters_minus_one,
			       fold_convert (iv_type, niters_skip));
  loop->nb_iterations = fold_build2 (TRUNC_DIV_EXPR, iv_type,
				     niters_adj2, iv_step);

  if (final_iv)
    {
      gassign *assign;
      /* If vectorizing an inverted early break loop we have to restart the
	 scalar loop at niters - vf.  This matches what we do in
	 vect_gen_vector_loop_niters_mult_vf for non-masked loops.  */
      if (LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo))
	{
	  tree ftype = TREE_TYPE (orig_niters);
	  tree vf = build_int_cst (ftype, LOOP_VINFO_VECT_FACTOR (loop_vinfo));
	  assign = gimple_build_assign (final_iv, MINUS_EXPR, orig_niters, vf);
	}
       else
	assign = gimple_build_assign (final_iv, orig_niters);
      gsi_insert_on_edge_immediate (exit_edge, assign);
    }

  return cond_stmt;
}


/* Like vect_set_loop_condition, but handle the case in which the vector
   loop handles exactly VF scalars per iteration.  */

static gcond *
vect_set_loop_condition_normal (loop_vec_info /* loop_vinfo */, edge exit_edge,
				class loop *loop, tree niters, tree step,
				tree final_iv, bool niters_maybe_zero,
				gimple_stmt_iterator loop_cond_gsi)
{
  tree indx_before_incr, indx_after_incr;
  gcond *cond_stmt;
  gcond *orig_cond;
  edge pe = loop_preheader_edge (loop);
  gimple_stmt_iterator incr_gsi;
  bool insert_after;
  enum tree_code code;
  tree niters_type = TREE_TYPE (niters);

  orig_cond = get_loop_exit_condition (exit_edge);
  gcc_assert (orig_cond);
  loop_cond_gsi = gsi_for_stmt (orig_cond);

  tree init, limit;
  if (!niters_maybe_zero && integer_onep (step))
    {
      /* In this case we can use a simple 0-based IV:

	 A:
	   x = 0;
	   do
	     {
	       ...
	       x += 1;
	     }
	   while (x < NITERS);  */
      code = (exit_edge->flags & EDGE_TRUE_VALUE) ? GE_EXPR : LT_EXPR;
      init = build_zero_cst (niters_type);
      limit = niters;
    }
  else
    {
      /* The following works for all values of NITERS except 0:

	 B:
	   x = 0;
	   do
	     {
	       ...
	       x += STEP;
	     }
	   while (x <= NITERS - STEP);

	 so that the loop continues to iterate if x + STEP - 1 < NITERS
	 but stops if x + STEP - 1 >= NITERS.

	 However, if NITERS is zero, x never hits a value above NITERS - STEP
	 before wrapping around.  There are two obvious ways of dealing with
	 this:

	 - start at STEP - 1 and compare x before incrementing it
	 - start at -1 and compare x after incrementing it

	 The latter is simpler and is what we use.  The loop in this case
	 looks like:

	 C:
	   x = -1;
	   do
	     {
	       ...
	       x += STEP;
	     }
	   while (x < NITERS - STEP);

	 In both cases the loop limit is NITERS - STEP.  */
      gimple_seq seq = NULL;
      limit = force_gimple_operand (niters, &seq, true, NULL_TREE);
      limit = gimple_build (&seq, MINUS_EXPR, TREE_TYPE (limit), limit, step);
      if (seq)
	{
	  basic_block new_bb = gsi_insert_seq_on_edge_immediate (pe, seq);
	  gcc_assert (!new_bb);
	}
      if (niters_maybe_zero)
	{
	  /* Case C.  */
	  code = (exit_edge->flags & EDGE_TRUE_VALUE) ? GE_EXPR : LT_EXPR;
	  init = build_all_ones_cst (niters_type);
	}
      else
	{
	  /* Case B.  */
	  code = (exit_edge->flags & EDGE_TRUE_VALUE) ? GT_EXPR : LE_EXPR;
	  init = build_zero_cst (niters_type);
	}
    }

  vect_iv_increment_position (exit_edge, &incr_gsi, &insert_after);
  create_iv (init, PLUS_EXPR, step, NULL_TREE, loop,
             &incr_gsi, insert_after, &indx_before_incr, &indx_after_incr);
  indx_after_incr = force_gimple_operand_gsi (&loop_cond_gsi, indx_after_incr,
					      true, NULL_TREE, true,
					      GSI_SAME_STMT);
  limit = force_gimple_operand_gsi (&loop_cond_gsi, limit, true, NULL_TREE,
				     true, GSI_SAME_STMT);

  cond_stmt = gimple_build_cond (code, indx_after_incr, limit, NULL_TREE,
				 NULL_TREE);

  gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);

  /* Record the number of latch iterations.  */
  if (limit == niters)
    /* Case A: the loop iterates NITERS times.  Subtract one to get the
       latch count.  */
    loop->nb_iterations = fold_build2 (MINUS_EXPR, niters_type, niters,
				       build_int_cst (niters_type, 1));
  else
    /* Case B or C: the loop iterates (NITERS - STEP) / STEP + 1 times.
       Subtract one from this to get the latch count.  */
    loop->nb_iterations = fold_build2 (TRUNC_DIV_EXPR, niters_type,
				       limit, step);

  if (final_iv)
    {
      gassign *assign;
      gcc_assert (single_pred_p (exit_edge->dest));
      tree phi_dest
	= integer_zerop (init) ? final_iv : copy_ssa_name (indx_after_incr);
      /* Make sure to maintain LC SSA form here and elide the subtraction
	 if the value is zero.  */
      gphi *phi = create_phi_node (phi_dest, exit_edge->dest);
      add_phi_arg (phi, indx_after_incr, exit_edge, UNKNOWN_LOCATION);
      if (!integer_zerop (init))
	{
	  assign = gimple_build_assign (final_iv, MINUS_EXPR,
					phi_dest, init);
	  gimple_stmt_iterator gsi = gsi_after_labels (exit_edge->dest);
	  gsi_insert_before (&gsi, assign, GSI_SAME_STMT);
	}
    }

  return cond_stmt;
}

/* If we're using fully-masked loops, make LOOP iterate:

      N == (NITERS - 1) / STEP + 1

   times.  When NITERS is zero, this is equivalent to making the loop
   execute (1 << M) / STEP times, where M is the precision of NITERS.
   NITERS_MAYBE_ZERO is true if this last case might occur.

   If we're not using fully-masked loops, make LOOP iterate:

      N == (NITERS - STEP) / STEP + 1

   times, where NITERS is known to be outside the range [1, STEP - 1].
   This is equivalent to making the loop execute NITERS / STEP times
   when NITERS is nonzero and (1 << M) / STEP times otherwise.
   NITERS_MAYBE_ZERO again indicates whether this last case might occur.

   If FINAL_IV is nonnull, it is an SSA name that should be set to
   N * STEP on exit from the loop.

   Assumption: the exit-condition of LOOP is the last stmt in the loop.  */

void
vect_set_loop_condition (class loop *loop, edge loop_e, loop_vec_info loop_vinfo,
			 tree niters, tree step, tree final_iv,
			 bool niters_maybe_zero)
{
  gcond *cond_stmt;
  gcond *orig_cond = get_loop_exit_condition (loop_e);
  gimple_stmt_iterator loop_cond_gsi = gsi_for_stmt (orig_cond);

  if (loop_vinfo && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
    {
      if (LOOP_VINFO_PARTIAL_VECTORS_STYLE (loop_vinfo) == vect_partial_vectors_avx512)
	cond_stmt = vect_set_loop_condition_partial_vectors_avx512 (loop, loop_e,
								    loop_vinfo,
								    niters, final_iv,
								    niters_maybe_zero,
								    loop_cond_gsi);
      else
	cond_stmt = vect_set_loop_condition_partial_vectors (loop, loop_e,
							     loop_vinfo,
							     niters, final_iv,
							     niters_maybe_zero,
							     loop_cond_gsi);
    }
  else
    cond_stmt = vect_set_loop_condition_normal (loop_vinfo, loop_e, loop,
						niters,
						step, final_iv,
						niters_maybe_zero,
						loop_cond_gsi);

  /* Remove old loop exit test.  */
  stmt_vec_info orig_cond_info;
  if (loop_vinfo
      && (orig_cond_info = loop_vinfo->lookup_stmt (orig_cond)))
    loop_vinfo->remove_stmt (orig_cond_info);
  else
    gsi_remove (&loop_cond_gsi, true);

  if (dump_enabled_p ())
    dump_printf_loc (MSG_NOTE, vect_location, "New loop exit condition: %G",
		     (gimple *) cond_stmt);
}

/* Get the virtual operand live on E.  The precondition on this is valid
   immediate dominators and an actual virtual definition dominating E.  */
/* ???  Costly band-aid.  For the use in question we can populate a
   live-on-exit/end-of-BB virtual operand when copying stmts.  */

static tree
get_live_virtual_operand_on_edge (edge e)
{
  basic_block bb = e->src;
  do
    {
      for (auto gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
	{
	  gimple *stmt = gsi_stmt (gsi);
	  if (gimple_vdef (stmt))
	    return gimple_vdef (stmt);
	  if (gimple_vuse (stmt))
	    return gimple_vuse (stmt);
	}
      if (gphi *vphi = get_virtual_phi (bb))
	return gimple_phi_result (vphi);
      bb = get_immediate_dominator (CDI_DOMINATORS, bb);
    }
  while (1);
}

/* Given LOOP this function generates a new copy of it and puts it
   on E which is either the entry or exit of LOOP.  If SCALAR_LOOP is
   non-NULL, assume LOOP and SCALAR_LOOP are equivalent and copy the
   basic blocks from SCALAR_LOOP instead of LOOP, but to either the
   entry or exit of LOOP.  If FLOW_LOOPS then connect LOOP to SCALAR_LOOP as a
   continuation.  This is correct for cases where one loop continues from the
   other like in the vectorizer, but not true for uses in e.g. loop distribution
   where the contents of the loop body are split but the iteration space of both
   copies remains the same.

   If UPDATED_DOMS is not NULL it is update with the list of basic blocks whoms
   dominators were updated during the peeling.  When doing early break vectorization
   then LOOP_VINFO needs to be provided and is used to keep track of any newly created
   memory references that need to be updated should we decide to vectorize.  */

class loop *
slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
					class loop *scalar_loop,
					edge scalar_exit, edge e, edge *new_e,
					bool flow_loops,
					vec<basic_block> *updated_doms)
{
  class loop *new_loop;
  basic_block *new_bbs, *bbs, *pbbs;
  bool at_exit;
  bool was_imm_dom;
  basic_block exit_dest;
  edge exit, new_exit;
  bool duplicate_outer_loop = false;

  exit = loop_exit;
  at_exit = (e == exit);
  if (!at_exit && e != loop_preheader_edge (loop))
    return NULL;

  if (scalar_loop == NULL)
    {
      scalar_loop = loop;
      scalar_exit = loop_exit;
    }
  else if (scalar_loop == loop)
    scalar_exit = loop_exit;
  else
    {
      /* Loop has been version, match exits up using the aux index.  */
      for (edge exit : get_loop_exit_edges (scalar_loop))
	if (exit->aux == loop_exit->aux)
	  {
	    scalar_exit	= exit;
	    break;
	  }

      gcc_assert (scalar_exit);
    }

  bbs = XNEWVEC (basic_block, scalar_loop->num_nodes + 1);
  pbbs = bbs + 1;
  get_loop_body_with_size (scalar_loop, pbbs, scalar_loop->num_nodes);
  /* Allow duplication of outer loops.  */
  if (scalar_loop->inner)
    duplicate_outer_loop = true;

  /* Generate new loop structure.  */
  new_loop = duplicate_loop (scalar_loop, loop_outer (scalar_loop));
  duplicate_subloops (scalar_loop, new_loop);

  exit_dest = exit->dest;
  was_imm_dom = (get_immediate_dominator (CDI_DOMINATORS,
					  exit_dest) == loop->header ?
		 true : false);

  /* Also copy the pre-header, this avoids jumping through hoops to
     duplicate the loop entry PHI arguments.  Create an empty
     pre-header unconditionally for this.  */
  basic_block preheader = split_edge (loop_preheader_edge (scalar_loop));
  edge entry_e = single_pred_edge (preheader);
  bbs[0] = preheader;
  new_bbs = XNEWVEC (basic_block, scalar_loop->num_nodes + 1);

  copy_bbs (bbs, scalar_loop->num_nodes + 1, new_bbs,
	    &scalar_exit, 1, &new_exit, NULL,
	    at_exit ? loop->latch : e->src, true);
  exit = loop_exit;
  basic_block new_preheader = new_bbs[0];

  gcc_assert (new_exit);

  /* Record the new loop exit information.  new_loop doesn't have SCEV data and
     so we must initialize the exit information.  */
  if (new_e)
    *new_e = new_exit;

  /* Before installing PHI arguments make sure that the edges
     into them match that of the scalar loop we analyzed.  This
     makes sure the SLP tree matches up between the main vectorized
     loop and the epilogue vectorized copies.  */
  if (single_succ_edge (preheader)->dest_idx
      != single_succ_edge (new_bbs[0])->dest_idx)
    {
      basic_block swap_bb = new_bbs[1];
      gcc_assert (EDGE_COUNT (swap_bb->preds) == 2);
      std::swap (EDGE_PRED (swap_bb, 0), EDGE_PRED (swap_bb, 1));
      EDGE_PRED (swap_bb, 0)->dest_idx = 0;
      EDGE_PRED (swap_bb, 1)->dest_idx = 1;
    }
  if (duplicate_outer_loop)
    {
      class loop *new_inner_loop = get_loop_copy (scalar_loop->inner);
      if (loop_preheader_edge (scalar_loop)->dest_idx
	  != loop_preheader_edge (new_inner_loop)->dest_idx)
	{
	  basic_block swap_bb = new_inner_loop->header;
	  gcc_assert (EDGE_COUNT (swap_bb->preds) == 2);
	  std::swap (EDGE_PRED (swap_bb, 0), EDGE_PRED (swap_bb, 1));
	  EDGE_PRED (swap_bb, 0)->dest_idx = 0;
	  EDGE_PRED (swap_bb, 1)->dest_idx = 1;
	}
    }

  add_phi_args_after_copy (new_bbs, scalar_loop->num_nodes + 1, NULL);

  /* Skip new preheader since it's deleted if copy loop is added at entry.  */
  for (unsigned i = (at_exit ? 0 : 1); i < scalar_loop->num_nodes + 1; i++)
    rename_variables_in_bb (new_bbs[i], duplicate_outer_loop);

  /* Rename the exit uses.  */
  for (edge exit : get_loop_exit_edges (new_loop))
    for (auto gsi = gsi_start_phis (exit->dest);
	 !gsi_end_p (gsi); gsi_next (&gsi))
      {
	tree orig_def = PHI_ARG_DEF_FROM_EDGE (gsi.phi (), exit);
	rename_use_op (PHI_ARG_DEF_PTR_FROM_EDGE (gsi.phi (), exit));
	if (MAY_HAVE_DEBUG_BIND_STMTS)
	  adjust_debug_stmts (orig_def, PHI_RESULT (gsi.phi ()), exit->dest);
      }

  auto loop_exits = get_loop_exit_edges (loop);
  bool multiple_exits_p = loop_exits.length () > 1;
  auto_vec<basic_block> doms;

  if (at_exit) /* Add the loop copy at exit.  */
    {
      if (scalar_loop != loop && new_exit->dest != exit_dest)
	{
	  new_exit = redirect_edge_and_branch (new_exit, exit_dest);
	  flush_pending_stmts (new_exit);
	}

      bool need_virtual_phi = get_virtual_phi (loop->header);

      /* For the main loop exit preserve the LC PHI nodes.  For vectorization
	 we need them to continue or finalize reductions.  Since we do not
	 copy the loop exit blocks we have to materialize PHIs at the
	 new destination before redirecting edges.  */
      for (auto gsi_from = gsi_start_phis (loop_exit->dest);
	   !gsi_end_p (gsi_from); gsi_next (&gsi_from))
	{
	  tree res = gimple_phi_result (*gsi_from);
	  create_phi_node (copy_ssa_name (res), new_preheader);
	}
      edge e = redirect_edge_and_branch (loop_exit, new_preheader);
      gcc_assert (e == loop_exit);
      flush_pending_stmts (loop_exit);
      set_immediate_dominator (CDI_DOMINATORS, new_preheader, loop_exit->src);

      /* If we ended up choosing an exit leading to a path not using memory
	 we can end up without a virtual LC PHI.  Create it when it is
	 needed because of the epilog loop continuation.  */
      if (need_virtual_phi && !get_virtual_phi (loop_exit->dest))
	{
	  tree header_def = gimple_phi_result (get_virtual_phi (loop->header));
	  gphi *vphi = create_phi_node (copy_ssa_name (header_def),
					new_preheader);
	  add_phi_arg (vphi, get_live_virtual_operand_on_edge (loop_exit),
		       loop_exit, UNKNOWN_LOCATION);
	}

      bool multiple_exits_p = loop_exits.length () > 1;
      basic_block main_loop_exit_block = new_preheader;
      basic_block alt_loop_exit_block = NULL;
      /* Create the CFG for multiple exits.
		   | loop_exit               | alt1   | altN
		   v                         v   ...  v
	    main_loop_exit_block:       alt_loop_exit_block:
		   |                      /
		   v                     v
	    new_preheader:
	 where in the new preheader we need merge PHIs for
	 the continuation values into the epilogue header.
	 Do not bother with exit PHIs for the early exits but
	 their live virtual operand.  We'll fix up things below.  */
      if (multiple_exits_p)
	{
	  edge loop_e = single_succ_edge (new_preheader);
	  new_preheader = split_edge (loop_e);

	  gphi *vphi = NULL;
	  alt_loop_exit_block = new_preheader;
	  for (auto exit : loop_exits)
	    if (exit != loop_exit)
	      {
		tree vphi_def = NULL_TREE;
		if (gphi *evphi = get_virtual_phi (exit->dest))
		  vphi_def = gimple_phi_arg_def_from_edge (evphi, exit);
		edge res = redirect_edge_and_branch (exit, alt_loop_exit_block);
		gcc_assert (res == exit);
		redirect_edge_var_map_clear (exit);
		if (alt_loop_exit_block == new_preheader)
		  alt_loop_exit_block = split_edge (exit);
		if (!need_virtual_phi)
		  continue;
		/* When the edge has no virtual LC PHI get at the live
		   virtual operand by other means.  */
		if (!vphi_def)
		  vphi_def = get_live_virtual_operand_on_edge (exit);
		if (!vphi)
		  vphi = create_phi_node (copy_ssa_name (vphi_def),
					  alt_loop_exit_block);
		else
		  /* Edge redirection might re-allocate the PHI node
		     so we have to rediscover it.  */
		  vphi = get_virtual_phi (alt_loop_exit_block);
		add_phi_arg (vphi, vphi_def, exit, UNKNOWN_LOCATION);
	      }

	  set_immediate_dominator (CDI_DOMINATORS, new_preheader,
				   loop->header);
	}

      /* Adjust the epilog loop PHI entry values to continue iteration.
	 This adds remaining necessary LC PHI nodes to the main exit
	 and creates merge PHIs when we have multiple exits with
	 their appropriate continuation.  */
      if (flow_loops)
	{
	  edge loop_entry = single_succ_edge (new_preheader);
	  bool peeled_iters = single_pred (loop->latch) != loop_exit->src;

	  /* Record the new SSA names in the cache so that we can skip
	     materializing them again when we fill in the rest of the LC SSA
	     variables.  */
	  hash_map <tree, tree> new_phi_args;
	  for (auto psi = gsi_start_phis (main_loop_exit_block);
	       !gsi_end_p (psi); gsi_next (&psi))
	    {
	      gphi *phi = *psi;
	      tree new_arg = gimple_phi_arg_def_from_edge (phi, loop_exit);
	      if (TREE_CODE (new_arg) != SSA_NAME)
		continue;

	      /* If the loop doesn't have a virtual def then only possibly keep
		 the epilog LC PHI for it and avoid creating new defs.  */
	      if (virtual_operand_p (new_arg) && !need_virtual_phi)
		{
		  auto gsi = gsi_for_stmt (phi);
		  remove_phi_node (&gsi, true);
		  continue;
		}

	      /* If we decided not to remove the PHI node we should also not
		 rematerialize it later on.  */
	      new_phi_args.put (new_arg, gimple_phi_result (phi));
	    }

	  /* Create the merge PHI nodes in new_preheader and populate the
	     arguments for the exits.  */
	  if (multiple_exits_p)
	    {
	      for (auto gsi_from = gsi_start_phis (loop->header),
		   gsi_to = gsi_start_phis (new_loop->header);
		   !gsi_end_p (gsi_from) && !gsi_end_p (gsi_to);
		   gsi_next (&gsi_from), gsi_next (&gsi_to))
		{
		  gimple *from_phi = gsi_stmt (gsi_from);
		  gimple *to_phi = gsi_stmt (gsi_to);

		  /* When the vector loop is peeled then we need to use the
		     value at start of the loop, otherwise the main loop exit
		     should use the final iter value.  */
		  tree new_arg;
		  if (peeled_iters)
		    new_arg = gimple_phi_result (from_phi);
		  else
		    new_arg = PHI_ARG_DEF_FROM_EDGE (from_phi,
						     loop_latch_edge (loop));

		  /* Check if we've already created a new phi node during edge
		     redirection and re-use it if so.  Otherwise create a
		     LC PHI node to feed the merge PHI.  */
		  tree *res;
		  if (virtual_operand_p (new_arg))
		    {
		      /* Use the existing virtual LC SSA from exit block.  */
		      gphi *vphi = get_virtual_phi (main_loop_exit_block);
		      new_arg = gimple_phi_result (vphi);
		    }
		  else if ((res = new_phi_args.get (new_arg)))
		    new_arg = *res;
		  else
		    {
		      /* Create the LC PHI node for the exit.  */
		      tree new_def = copy_ssa_name (new_arg);
		      gphi *lc_phi
			  = create_phi_node (new_def, main_loop_exit_block);
		      SET_PHI_ARG_DEF (lc_phi, 0, new_arg);
		      new_arg = new_def;
		    }

		  /* Create the PHI node in the merge block merging the
		     main and early exit values.  */
		  tree new_res = copy_ssa_name (gimple_phi_result (from_phi));
		  gphi *lcssa_phi = create_phi_node (new_res, new_preheader);
		  edge main_e = single_succ_edge (main_loop_exit_block);
		  SET_PHI_ARG_DEF_ON_EDGE (lcssa_phi, main_e, new_arg);

		  /* And adjust the epilog entry value.  */
		  adjust_phi_and_debug_stmts (to_phi, loop_entry, new_res);
		}

	      /* After creating the merge PHIs handle the early exits those
		 should use the values at the start of the loop.  */
	      for (auto gsi_from = gsi_start_phis (loop->header),
		   gsi_to = gsi_start_phis (new_preheader);
		   !gsi_end_p (gsi_from) && !gsi_end_p (gsi_to);
		   gsi_next (&gsi_from), gsi_next (&gsi_to))
		{
		  gimple *from_phi = gsi_stmt (gsi_from);
		  gimple *to_phi = gsi_stmt (gsi_to);

		  /* Now update the virtual PHI nodes with the right value.  */
		  tree alt_arg = gimple_phi_result (from_phi);
		  if (virtual_operand_p (alt_arg))
		    {
		      gphi *vphi = get_virtual_phi (alt_loop_exit_block);
		      alt_arg = gimple_phi_result (vphi);
		    }
		  /* For other live args we didn't create LC PHI nodes.
		     Do so here.  */
		  else
		    {
		      tree alt_def = copy_ssa_name (alt_arg);
		      gphi *lc_phi
			= create_phi_node (alt_def, alt_loop_exit_block);
		      for (unsigned i = 0; i < gimple_phi_num_args (lc_phi);
			   ++i)
			SET_PHI_ARG_DEF (lc_phi, i, alt_arg);
		      alt_arg = alt_def;
		    }
		  edge alt_e = single_succ_edge (alt_loop_exit_block);
		  SET_PHI_ARG_DEF_ON_EDGE (to_phi, alt_e, alt_arg);
		}
	    }
	  /* For the single exit case only create the missing LC PHI nodes
	     for the continuation of the loop IVs that are not also already
	     reductions and thus had LC PHI nodes on the exit already.  */
	  else
	    {
	      for (auto gsi_from = gsi_start_phis (loop->header),
		   gsi_to = gsi_start_phis (new_loop->header);
		   !gsi_end_p (gsi_from) && !gsi_end_p (gsi_to);
		   gsi_next (&gsi_from), gsi_next (&gsi_to))
		{
		  gimple *from_phi = gsi_stmt (gsi_from);
		  gimple *to_phi = gsi_stmt (gsi_to);
		  tree new_arg = PHI_ARG_DEF_FROM_EDGE (from_phi,
							loop_latch_edge (loop));

		  /* Check if we've already created a new phi node during edge
		     redirection.  If we have, only propagate the value
		     downwards.  */
		  if (tree *res = new_phi_args.get (new_arg))
		    {
		      adjust_phi_and_debug_stmts (to_phi, loop_entry, *res);
		      continue;
		    }

		  tree new_res = copy_ssa_name (gimple_phi_result (from_phi));
		  gphi *lcssa_phi = create_phi_node (new_res, new_preheader);
		  SET_PHI_ARG_DEF_ON_EDGE (lcssa_phi, loop_exit, new_arg);
		  adjust_phi_and_debug_stmts (to_phi, loop_entry, new_res);
		}
	    }
	}

      if (was_imm_dom || duplicate_outer_loop)
	set_immediate_dominator (CDI_DOMINATORS, exit_dest, new_exit->src);

      /* And remove the non-necessary forwarder again.  Keep the other
         one so we have a proper pre-header for the loop at the exit edge.  */
      redirect_edge_pred (single_succ_edge (preheader),
			  single_pred (preheader));
      delete_basic_block (preheader);
      set_immediate_dominator (CDI_DOMINATORS, scalar_loop->header,
			       loop_preheader_edge (scalar_loop)->src);

      /* Finally after wiring the new epilogue we need to update its main exit
	 to the original function exit we recorded.  Other exits are already
	 correct.  */
      if (multiple_exits_p)
	{
	  class loop *update_loop = new_loop;
	  doms = get_all_dominated_blocks (CDI_DOMINATORS, loop->header);
	  for (unsigned i = 0; i < doms.length (); ++i)
	    if (flow_bb_inside_loop_p (loop, doms[i]))
	      doms.unordered_remove (i);

	  for (edge e : get_loop_exit_edges (update_loop))
	    {
	      edge ex;
	      edge_iterator ei;
	      FOR_EACH_EDGE (ex, ei, e->dest->succs)
		{
		  /* Find the first non-fallthrough block as fall-throughs can't
		     dominate other blocks.  */
		  if (single_succ_p (ex->dest))
		    {
		      doms.safe_push (ex->dest);
		      ex = single_succ_edge (ex->dest);
		    }
		  doms.safe_push (ex->dest);
		}
	      doms.safe_push (e->dest);
	    }

	  iterate_fix_dominators (CDI_DOMINATORS, doms, false);
	  if (updated_doms)
	    updated_doms->safe_splice (doms);
	}
    }
  else /* Add the copy at entry.  */
    {
      /* Copy the current loop LC PHI nodes between the original loop exit
	 block and the new loop header.  This allows us to later split the
	 preheader block and still find the right LC nodes.  */
      if (flow_loops)
	for (auto gsi_from = gsi_start_phis (new_loop->header),
	     gsi_to = gsi_start_phis (loop->header);
	     !gsi_end_p (gsi_from) && !gsi_end_p (gsi_to);
	     gsi_next (&gsi_from), gsi_next (&gsi_to))
	  {
	    gimple *from_phi = gsi_stmt (gsi_from);
	    gimple *to_phi = gsi_stmt (gsi_to);
	    tree new_arg = PHI_ARG_DEF_FROM_EDGE (from_phi,
						  loop_latch_edge (new_loop));
	    adjust_phi_and_debug_stmts (to_phi, loop_preheader_edge (loop),
					new_arg);
	  }

      if (scalar_loop != loop)
	{
	  /* Remove the non-necessary forwarder of scalar_loop again.  */
	  redirect_edge_pred (single_succ_edge (preheader),
			      single_pred (preheader));
	  delete_basic_block (preheader);
	  set_immediate_dominator (CDI_DOMINATORS, scalar_loop->header,
				   loop_preheader_edge (scalar_loop)->src);
	  preheader = split_edge (loop_preheader_edge (loop));
	  entry_e = single_pred_edge (preheader);
	}

      redirect_edge_and_branch_force (entry_e, new_preheader);
      flush_pending_stmts (entry_e);
      set_immediate_dominator (CDI_DOMINATORS, new_preheader, entry_e->src);

      redirect_edge_and_branch_force (new_exit, preheader);
      flush_pending_stmts (new_exit);
      set_immediate_dominator (CDI_DOMINATORS, preheader, new_exit->src);

      /* And remove the non-necessary forwarder again.  Keep the other
         one so we have a proper pre-header for the loop at the exit edge.  */
      redirect_edge_pred (single_succ_edge (new_preheader),
			  single_pred (new_preheader));
      delete_basic_block (new_preheader);
      set_immediate_dominator (CDI_DOMINATORS, new_loop->header,
			       loop_preheader_edge (new_loop)->src);

      /* Update dominators for multiple exits.  */
      if (multiple_exits_p)
	{
	  for (edge alt_e : loop_exits)
	    {
	      if (alt_e == loop_exit)
		continue;
	      basic_block old_dom
		= get_immediate_dominator (CDI_DOMINATORS, alt_e->dest);
	      if (flow_bb_inside_loop_p (loop, old_dom))
		{
		  auto_vec<basic_block, 8> queue;
		  for (auto son = first_dom_son (CDI_DOMINATORS, old_dom);
		       son; son = next_dom_son (CDI_DOMINATORS, son))
		    if (!flow_bb_inside_loop_p (loop, son))
		      queue.safe_push (son);
		  for (auto son : queue)
		    set_immediate_dominator (CDI_DOMINATORS,
					     son, get_bb_copy (old_dom));
		}
	    }
	}
    }

  free (new_bbs);
  free (bbs);

  checking_verify_dominators (CDI_DOMINATORS);

  return new_loop;
}


/* Given the condition expression COND, put it as the last statement of
   GUARD_BB; set both edges' probability; set dominator of GUARD_TO to
   DOM_BB; return the skip edge.  GUARD_TO is the target basic block to
   skip the loop.  PROBABILITY is the skip edge's probability.  Mark the
   new edge as irreducible if IRREDUCIBLE_P is true.  */

static edge
slpeel_add_loop_guard (basic_block guard_bb, tree cond,
		       basic_block guard_to, basic_block dom_bb,
		       profile_probability probability, bool irreducible_p)
{
  gimple_stmt_iterator gsi;
  edge new_e, enter_e;
  gcond *cond_stmt;
  gimple_seq gimplify_stmt_list = NULL;

  enter_e = EDGE_SUCC (guard_bb, 0);
  enter_e->flags &= ~EDGE_FALLTHRU;
  enter_e->flags |= EDGE_FALSE_VALUE;
  gsi = gsi_last_bb (guard_bb);

  cond = force_gimple_operand_1 (cond, &gimplify_stmt_list,
				 is_gimple_condexpr_for_cond, NULL_TREE);
  if (gimplify_stmt_list)
    gsi_insert_seq_after (&gsi, gimplify_stmt_list, GSI_NEW_STMT);

  cond_stmt = gimple_build_cond_from_tree (cond, NULL_TREE, NULL_TREE);
  gsi = gsi_last_bb (guard_bb);
  gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);

  /* Add new edge to connect guard block to the merge/loop-exit block.  */
  new_e = make_edge (guard_bb, guard_to, EDGE_TRUE_VALUE);

  new_e->probability = probability;
  if (irreducible_p)
    new_e->flags |= EDGE_IRREDUCIBLE_LOOP;

  enter_e->probability = probability.invert ();
  set_immediate_dominator (CDI_DOMINATORS, guard_to, dom_bb);

  /* Split enter_e to preserve LOOPS_HAVE_PREHEADERS.  */
  if (enter_e->dest->loop_father->header == enter_e->dest)
    split_edge (enter_e);

  return new_e;
}


/* This function verifies that the following restrictions apply to LOOP:
   (1) it consists of exactly 2 basic blocks - header, and an empty latch
       for innermost loop and 5 basic blocks for outer-loop.
   (2) it is single entry, single exit
   (3) its exit condition is the last stmt in the header
   (4) E is the entry/exit edge of LOOP.
 */

bool
slpeel_can_duplicate_loop_p (const class loop *loop, const_edge exit_e,
			     const_edge e)
{
  edge entry_e = loop_preheader_edge (loop);
  gcond *orig_cond = get_loop_exit_condition (exit_e);
  gimple_stmt_iterator loop_exit_gsi = gsi_last_bb (exit_e->src);

  /* All loops have an outer scope; the only case loop->outer is NULL is for
     the function itself.  */
  if (!loop_outer (loop)
      || !empty_block_p (loop->latch)
      || !exit_e
      /* Verify that new loop exit condition can be trivially modified.  */
      || (!orig_cond || orig_cond != gsi_stmt (loop_exit_gsi))
      || (e != exit_e && e != entry_e))
    return false;

  basic_block *bbs = XNEWVEC (basic_block, loop->num_nodes);
  get_loop_body_with_size (loop, bbs, loop->num_nodes);
  bool ret = can_copy_bbs_p (bbs, loop->num_nodes);
  free (bbs);
  return ret;
}

/* Function find_loop_location.

   Extract the location of the loop in the source code.
   If the loop is not well formed for vectorization, an estimated
   location is calculated.
   Return the loop location if succeed and NULL if not.  */

dump_user_location_t
find_loop_location (class loop *loop)
{
  gimple *stmt = NULL;
  basic_block bb;
  gimple_stmt_iterator si;

  if (!loop)
    return dump_user_location_t ();

  /* For the root of the loop tree return the function location.  */
  if (!loop_outer (loop))
    return dump_user_location_t::from_function_decl (cfun->decl);

  if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
    {
      /* We only care about the loop location, so use any exit with location
	 information.  */
      for (edge e : get_loop_exit_edges (loop))
	{
	  stmt = get_loop_exit_condition (e);

	  if (stmt
	      && LOCATION_LOCUS (gimple_location (stmt)) > BUILTINS_LOCATION)
	    return stmt;
	}
    }

  /* If we got here the loop is probably not "well formed",
     try to estimate the loop location */

  if (!loop->header)
    return dump_user_location_t ();

  bb = loop->header;

  for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
    {
      stmt = gsi_stmt (si);
      if (LOCATION_LOCUS (gimple_location (stmt)) > BUILTINS_LOCATION)
        return stmt;
    }

  return dump_user_location_t ();
}

/* Return true if the phi described by STMT_INFO defines an IV of the
   loop to be vectorized.  */

static bool
iv_phi_p (stmt_vec_info stmt_info)
{
  gphi *phi = as_a <gphi *> (stmt_info->stmt);
  if (virtual_operand_p (PHI_RESULT (phi)))
    return false;

  if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def
      || STMT_VINFO_DEF_TYPE (stmt_info) == vect_double_reduction_def)
    return false;

  return true;
}

/* Return true if vectorizer can peel for nonlinear iv.  */
static bool
vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
			      stmt_vec_info stmt_info)
{
  enum vect_induction_op_type induction_type
    = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info);
  tree niters_skip;
  /* Init_expr will be update by vect_update_ivs_after_vectorizer,
     if niters or vf is unkown:
     For shift, when shift mount >= precision, there would be UD.
     For mult, don't known how to generate
     init_expr * pow (step, niters) for variable niters.
     For neg unknown niters are ok, since niters of vectorized main loop
     will always be multiple of 2.
     See also PR113163,  PR114196 and PR114485.  */
  if (!LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ()
      || LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
      || (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
	  && induction_type != vect_step_op_neg))
    {
      if (dump_enabled_p ())
	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
			 "Peeling for epilogue is not supported"
			 " for this nonlinear induction"
			 " when iteration count is unknown or"
			 " when using partial vectorization.\n");
      return false;
    }

  /* Avoid compile time hog on vect_peel_nonlinear_iv_init.  */
  if (induction_type == vect_step_op_mul)
    {
      tree step_expr = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (stmt_info);
      tree type = TREE_TYPE (step_expr);

      if (wi::exact_log2 (wi::to_wide (step_expr)) == -1
	  && LOOP_VINFO_INT_NITERS(loop_vinfo) >= TYPE_PRECISION (type))
	{
	  if (dump_enabled_p ())
	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
			     "Avoid compile time hog on"
			     " vect_peel_nonlinear_iv_init"
			     " for nonlinear induction vec_step_op_mul"
			     " when iteration count is too big.\n");
	  return false;
	}
    }

  /* Also doens't support peel for neg when niter is variable.
     ??? generate something like niter_expr & 1 ? init_expr : -init_expr?  */
  niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
  if ((niters_skip != NULL_TREE
       && (TREE_CODE (niters_skip) != INTEGER_CST
	   || (HOST_WIDE_INT) TREE_INT_CST_LOW (niters_skip) < 0))
      || (!vect_use_loop_mask_for_alignment_p (loop_vinfo)
	  && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) < 0))
    {
      if (dump_enabled_p ())
	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
			 "Peeling for alignement is not supported"
			 " for nonlinear induction when niters_skip"
			 " is not constant.\n");
      return false;
    }

  return true;
}

/* Function vect_can_advance_ivs_p

   In case the number of iterations that LOOP iterates is unknown at compile
   time, an epilog loop will be generated, and the loop induction variables
   (IVs) will be "advanced" to the value they are supposed to take just before
   the epilog loop.  Here we check that the access function of the loop IVs
   and the expression that represents the loop bound are simple enough.
   These restrictions will be relaxed in the future.  */

bool
vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
{
  class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
  basic_block bb = loop->header;
  gphi_iterator gsi;

  /* Analyze phi functions of the loop header.  */

  if (dump_enabled_p ())
    dump_printf_loc (MSG_NOTE, vect_location, "vect_can_advance_ivs_p:\n");
  for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
    {
      tree evolution_part;
      enum vect_induction_op_type induction_type;

      gphi *phi = gsi.phi ();
      stmt_vec_info phi_info = loop_vinfo->lookup_stmt (phi);
      if (dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location, "Analyze phi: %G",
			 phi_info->stmt);

      /* Skip virtual phi's. The data dependences that are associated with
	 virtual defs/uses (i.e., memory accesses) are analyzed elsewhere.

	 Skip reduction phis.  */
      if (!iv_phi_p (phi_info))
	{
	  if (dump_enabled_p ())
	    dump_printf_loc (MSG_NOTE, vect_location,
			     "reduc or virtual phi. skip.\n");
	  continue;
	}

      induction_type = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (phi_info);
      if (induction_type != vect_step_op_add)
	{
	  if (!vect_can_peel_nonlinear_iv_p (loop_vinfo, phi_info))
	    return false;

	  continue;
	}

      /* Analyze the evolution function.  */

      evolution_part = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (phi_info);
      if (evolution_part == NULL_TREE)
        {
	  if (dump_enabled_p ())
	    dump_printf (MSG_MISSED_OPTIMIZATION,
			 "No access function or evolution.\n");
	  return false;
        }

      /* FORNOW: We do not transform initial conditions of IVs
	 which evolution functions are not invariants in the loop.  */

      if (!expr_invariant_in_loop_p (loop, evolution_part))
	{
	  if (dump_enabled_p ())
	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
			     "evolution not invariant in loop.\n");
	  return false;
	}

      /* FORNOW: We do not transform initial conditions of IVs
	 which evolution functions are a polynomial of degree >= 2.  */

      if (tree_is_chrec (evolution_part))
	{
	  if (dump_enabled_p ())
	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
			     "evolution is chrec.\n");
	  return false;
	}
    }

  return true;
}


/*   Function vect_update_ivs_after_vectorizer.

     "Advance" the induction variables of LOOP to the value they should take
     after the execution of LOOP.  This is currently necessary because the
     vectorizer does not handle induction variables that are used after the
     loop.  Such a situation occurs when the last iterations of LOOP are
     peeled, because:
     1. We introduced new uses after LOOP for IVs that were not originally used
        after LOOP: the IVs of LOOP are now used by an epilog loop.
     2. LOOP is going to be vectorized; this means that it will iterate N/VF
        times, whereas the loop IVs should be bumped N times.

     Input:
     - LOOP - a loop that is going to be vectorized. The last few iterations
              of LOOP were peeled.
     - NITERS - the number of iterations that LOOP executes (before it is
                vectorized). i.e, the number of times the ivs should be bumped.
     - UPDATE_E - a successor edge of LOOP->exit that is on the (only) path
                  coming out from LOOP on which there are uses of the LOOP ivs
		  (this is the path from LOOP->exit to epilog_loop->preheader).

                  The new definitions of the ivs are placed in LOOP->exit.
                  The phi args associated with the edge UPDATE_E in the bb
                  UPDATE_E->dest are updated accordingly.

     Assumption 1: Like the rest of the vectorizer, this function assumes
     a single loop exit that has a single predecessor.

     Assumption 2: The phi nodes in the LOOP header and in update_bb are
     organized in the same order.

     Assumption 3: The access function of the ivs is simple enough (see
     vect_can_advance_ivs_p).  This assumption will be relaxed in the future.

     Assumption 4: Exactly one of the successors of LOOP exit-bb is on a path
     coming out of LOOP on which the ivs of LOOP are used (this is the path
     that leads to the epilog loop; other paths skip the epilog loop).  This
     path starts with the edge UPDATE_E, and its destination (denoted update_bb)
     needs to have its phis updated.
 */

static void
vect_update_ivs_after_vectorizer (loop_vec_info loop_vinfo,
				  tree niters, edge update_e)
{
  gphi_iterator gsi, gsi1;
  class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
  basic_block update_bb = update_e->dest;
  basic_block exit_bb = LOOP_VINFO_IV_EXIT (loop_vinfo)->dest;
  gimple_stmt_iterator last_gsi = gsi_last_bb (exit_bb);

  for (gsi = gsi_start_phis (loop->header), gsi1 = gsi_start_phis (update_bb);
       !gsi_end_p (gsi) && !gsi_end_p (gsi1);
       gsi_next (&gsi), gsi_next (&gsi1))
    {
      tree init_expr;
      tree step_expr, off;
      tree type;
      tree var, ni, ni_name;

      gphi *phi = gsi.phi ();
      gphi *phi1 = gsi1.phi ();
      stmt_vec_info phi_info = loop_vinfo->lookup_stmt (phi);
      if (dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location,
			 "vect_update_ivs_after_vectorizer: phi: %G",
			 (gimple *) phi);

      /* Skip reduction and virtual phis.  */
      if (!iv_phi_p (phi_info))
	{
	  if (dump_enabled_p ())
	    dump_printf_loc (MSG_NOTE, vect_location,
			     "reduc or virtual phi. skip.\n");
	  continue;
	}

      type = TREE_TYPE (gimple_phi_result (phi));
      step_expr = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (phi_info);
      step_expr = unshare_expr (step_expr);

      /* FORNOW: We do not support IVs whose evolution function is a polynomial
         of degree >= 2 or exponential.  */
      gcc_assert (!tree_is_chrec (step_expr));

      init_expr = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop));
      gimple_seq stmts = NULL;
      enum vect_induction_op_type induction_type
	= STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (phi_info);

      if (induction_type == vect_step_op_add)
	{
	  tree stype = TREE_TYPE (step_expr);
	  off = fold_build2 (MULT_EXPR, stype,
			       fold_convert (stype, niters), step_expr);

	  if (POINTER_TYPE_P (type))
	    ni = fold_build_pointer_plus (init_expr, off);
	  else
	    ni = fold_convert (type,
			       fold_build2 (PLUS_EXPR, stype,
					    fold_convert (stype, init_expr),
					    off));
	}
      /* Don't bother call vect_peel_nonlinear_iv_init.  */
      else if (induction_type == vect_step_op_neg)
	ni = init_expr;
      else
	ni = vect_peel_nonlinear_iv_init (&stmts, init_expr,
					  niters, step_expr,
					  induction_type);

      var = create_tmp_var (type, "tmp");

      gimple_seq new_stmts = NULL;
      ni_name = force_gimple_operand (ni, &new_stmts, false, var);

      /* Exit_bb shouldn't be empty.  */
      if (!gsi_end_p (last_gsi))
	{
	  gsi_insert_seq_after (&last_gsi, stmts, GSI_SAME_STMT);
	  gsi_insert_seq_after (&last_gsi, new_stmts, GSI_SAME_STMT);
	}
      else
	{
	  gsi_insert_seq_before (&last_gsi, stmts, GSI_SAME_STMT);
	  gsi_insert_seq_before (&last_gsi, new_stmts, GSI_SAME_STMT);
	}

      /* Fix phi expressions in the successor bb.  */
      adjust_phi_and_debug_stmts (phi1, update_e, ni_name);
    }
}

/* Return a gimple value containing the misalignment (measured in vector
   elements) for the loop described by LOOP_VINFO, i.e. how many elements
   it is away from a perfectly aligned address.  Add any new statements
   to SEQ.  */

static tree
get_misalign_in_elems (gimple **seq, loop_vec_info loop_vinfo)
{
  dr_vec_info *dr_info = LOOP_VINFO_UNALIGNED_DR (loop_vinfo);
  stmt_vec_info stmt_info = dr_info->stmt;
  tree vectype = STMT_VINFO_VECTYPE (stmt_info);

  poly_uint64 target_align = DR_TARGET_ALIGNMENT (dr_info);
  unsigned HOST_WIDE_INT target_align_c;
  tree target_align_minus_1;

  bool negative = tree_int_cst_compare (DR_STEP (dr_info->dr),
					size_zero_node) < 0;
  tree offset = (negative
		 ? size_int ((-TYPE_VECTOR_SUBPARTS (vectype) + 1)
			     * TREE_INT_CST_LOW
				 (TYPE_SIZE_UNIT (TREE_TYPE (vectype))))
		 : size_zero_node);
  tree start_addr = vect_create_addr_base_for_vector_ref (loop_vinfo,
							  stmt_info, seq,
							  offset);
  tree type = unsigned_type_for (TREE_TYPE (start_addr));
  if (target_align.is_constant (&target_align_c))
    target_align_minus_1 = build_int_cst (type, target_align_c - 1);
  else
    {
      tree vla = build_int_cst (type, target_align);
      tree vla_align = fold_build2 (BIT_AND_EXPR, type, vla,
				    fold_build2 (MINUS_EXPR, type,
						 build_int_cst (type, 0), vla));
      target_align_minus_1 = fold_build2 (MINUS_EXPR, type, vla_align,
					  build_int_cst (type, 1));
    }

  HOST_WIDE_INT elem_size
    = int_cst_value (TYPE_SIZE_UNIT (TREE_TYPE (vectype)));
  tree elem_size_log = build_int_cst (type, exact_log2 (elem_size));

  /* Create:  misalign_in_bytes = addr & (target_align - 1).  */
  tree int_start_addr = fold_convert (type, start_addr);
  tree misalign_in_bytes = fold_build2 (BIT_AND_EXPR, type, int_start_addr,
					target_align_minus_1);

  /* Create:  misalign_in_elems = misalign_in_bytes / element_size.  */
  tree misalign_in_elems = fold_build2 (RSHIFT_EXPR, type, misalign_in_bytes,
					elem_size_log);

  return misalign_in_elems;
}

/* Function vect_gen_prolog_loop_niters

   Generate the number of iterations which should be peeled as prolog for the
   loop represented by LOOP_VINFO.  It is calculated as the misalignment of
   DR - the data reference recorded in LOOP_VINFO_UNALIGNED_DR (LOOP_VINFO).
   As a result, after the execution of this loop, the data reference DR will
   refer to an aligned location.  The following computation is generated:

   If the misalignment of DR is known at compile time:
     addr_mis = int mis = DR_MISALIGNMENT (dr);
   Else, compute address misalignment in bytes:
     addr_mis = addr & (target_align - 1)

   prolog_niters = ((VF - addr_mis/elem_size)&(VF-1))/step

   (elem_size = element type size; an element is the scalar element whose type
   is the inner type of the vectype)

   The computations will be emitted at the end of BB.  We also compute and
   store upper bound (included) of the result in BOUND.

   When the step of the data-ref in the loop is not 1 (as in interleaved data
   and SLP), the number of iterations of the prolog must be divided by the step
   (which is equal to the size of interleaved group).

   The above formulas assume that VF == number of elements in the vector. This
   may not hold when there are multiple-types in the loop.
   In this case, for some data-references in the loop the VF does not represent
   the number of elements that fit in the vector.  Therefore, instead of VF we
   use TYPE_VECTOR_SUBPARTS.  */

static tree
vect_gen_prolog_loop_niters (loop_vec_info loop_vinfo,
			     basic_block bb, int *bound)
{
  dr_vec_info *dr_info = LOOP_VINFO_UNALIGNED_DR (loop_vinfo);
  tree var;
  tree niters_type = TREE_TYPE (LOOP_VINFO_NITERS (loop_vinfo));
  gimple_seq stmts = NULL, new_stmts = NULL;
  tree iters, iters_name;
  stmt_vec_info stmt_info = dr_info->stmt;
  tree vectype = STMT_VINFO_VECTYPE (stmt_info);
  poly_uint64 target_align = DR_TARGET_ALIGNMENT (dr_info);

  if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) > 0)
    {
      int npeel = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);

      if (dump_enabled_p ())
        dump_printf_loc (MSG_NOTE, vect_location,
                         "known peeling = %d.\n", npeel);

      iters = build_int_cst (niters_type, npeel);
      *bound = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);
    }
  else
    {
      tree misalign_in_elems = get_misalign_in_elems (&stmts, loop_vinfo);
      tree type = TREE_TYPE (misalign_in_elems);
      HOST_WIDE_INT elem_size
	= int_cst_value (TYPE_SIZE_UNIT (TREE_TYPE (vectype)));
      /* We only do prolog peeling if the target alignment is known at compile
         time.  */
      poly_uint64 align_in_elems =
	exact_div (target_align, elem_size);
      tree align_in_elems_minus_1 =
	build_int_cst (type, align_in_elems - 1);
      tree align_in_elems_tree = build_int_cst (type, align_in_elems);

      /* Create:  (niters_type) ((align_in_elems - misalign_in_elems)
				 & (align_in_elems - 1)).  */
      bool negative = tree_int_cst_compare (DR_STEP (dr_info->dr),
					    size_zero_node) < 0;
      if (negative)
	iters = fold_build2 (MINUS_EXPR, type, misalign_in_elems,
			     align_in_elems_tree);
      else
	iters = fold_build2 (MINUS_EXPR, type, align_in_elems_tree,
			     misalign_in_elems);
      iters = fold_build2 (BIT_AND_EXPR, type, iters, align_in_elems_minus_1);
      iters = fold_convert (niters_type, iters);
      unsigned HOST_WIDE_INT align_in_elems_c;
      if (align_in_elems.is_constant (&align_in_elems_c))
	*bound = align_in_elems_c - 1;
      else
	*bound = -1;
    }

  if (dump_enabled_p ())
    dump_printf_loc (MSG_NOTE, vect_location,
		     "niters for prolog loop: %T\n", iters);

  var = create_tmp_var (niters_type, "prolog_loop_niters");
  iters_name = force_gimple_operand (iters, &new_stmts, false, var);

  if (new_stmts)
    gimple_seq_add_seq (&stmts, new_stmts);
  if (stmts)
    {
      gcc_assert (single_succ_p (bb));
      gimple_stmt_iterator gsi = gsi_last_bb (bb);
      if (gsi_end_p (gsi))
	gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT);
      else
	gsi_insert_seq_after (&gsi, stmts, GSI_SAME_STMT);
    }
  return iters_name;
}


/* Function vect_update_init_of_dr

   If CODE is PLUS, the vector loop starts NITERS iterations after the
   scalar one, otherwise CODE is MINUS and the vector loop starts NITERS
   iterations before the scalar one (using masking to skip inactive
   elements).  This function updates the information recorded in DR to
   account for the difference.  Specifically, it updates the OFFSET
   field of DR_INFO.  */

static void
vect_update_init_of_dr (dr_vec_info *dr_info, tree niters, tree_code code)
{
  struct data_reference *dr = dr_info->dr;
  tree offset = dr_info->offset;
  if (!offset)
    offset = build_zero_cst (sizetype);

  niters = fold_build2 (MULT_EXPR, sizetype,
			fold_convert (sizetype, niters),
			fold_convert (sizetype, DR_STEP (dr)));
  offset = fold_build2 (code, sizetype,
			fold_convert (sizetype, offset), niters);
  dr_info->offset = offset;
}


/* Function vect_update_inits_of_drs

   Apply vect_update_inits_of_dr to all accesses in LOOP_VINFO.
   CODE and NITERS are as for vect_update_inits_of_dr.  */

void
vect_update_inits_of_drs (loop_vec_info loop_vinfo, tree niters,
			  tree_code code)
{
  unsigned int i;
  vec<data_reference_p> datarefs = LOOP_VINFO_DATAREFS (loop_vinfo);
  struct data_reference *dr;

  DUMP_VECT_SCOPE ("vect_update_inits_of_dr");

  /* Adjust niters to sizetype.  We used to insert the stmts on loop preheader
     here, but since we might use these niters to update the epilogues niters
     and data references we can't insert them here as this definition might not
     always dominate its uses.  */
  if (!types_compatible_p (sizetype, TREE_TYPE (niters)))
    niters = fold_convert (sizetype, niters);

  FOR_EACH_VEC_ELT (datarefs, i, dr)
    {
      dr_vec_info *dr_info = loop_vinfo->lookup_dr (dr);
      if (!STMT_VINFO_GATHER_SCATTER_P (dr_info->stmt)
	  && !STMT_VINFO_SIMD_LANE_ACCESS_P (dr_info->stmt))
	vect_update_init_of_dr (dr_info, niters, code);
    }
}

/* For the information recorded in LOOP_VINFO prepare the loop for peeling
   by masking.  This involves calculating the number of iterations to
   be peeled and then aligning all memory references appropriately.  */

void
vect_prepare_for_masked_peels (loop_vec_info loop_vinfo)
{
  tree misalign_in_elems;
  tree type = TREE_TYPE (LOOP_VINFO_NITERS (loop_vinfo));

  gcc_assert (vect_use_loop_mask_for_alignment_p (loop_vinfo));

  /* From the information recorded in LOOP_VINFO get the number of iterations
     that need to be skipped via masking.  */
  if (LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) > 0)
    {
      poly_int64 misalign = (LOOP_VINFO_VECT_FACTOR (loop_vinfo)
			     - LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo));
      misalign_in_elems = build_int_cst (type, misalign);
    }
  else
    {
      gimple_seq seq1 = NULL, seq2 = NULL;
      misalign_in_elems = get_misalign_in_elems (&seq1, loop_vinfo);
      misalign_in_elems = fold_convert (type, misalign_in_elems);
      misalign_in_elems = force_gimple_operand (misalign_in_elems,
						&seq2, true, NULL_TREE);
      gimple_seq_add_seq (&seq1, seq2);
      if (seq1)
	{
	  edge pe = loop_preheader_edge (LOOP_VINFO_LOOP (loop_vinfo));
	  basic_block new_bb = gsi_insert_seq_on_edge_immediate (pe, seq1);
	  gcc_assert (!new_bb);
	}
    }

  if (dump_enabled_p ())
    dump_printf_loc (MSG_NOTE, vect_location,
		     "misalignment for fully-masked loop: %T\n",
		     misalign_in_elems);

  LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo) = misalign_in_elems;

  vect_update_inits_of_drs (loop_vinfo, misalign_in_elems, MINUS_EXPR);
}

/* This function builds ni_name = number of iterations.  Statements
   are emitted on the loop preheader edge.  If NEW_VAR_P is not NULL, set
   it to TRUE if new ssa_var is generated.  */

tree
vect_build_loop_niters (loop_vec_info loop_vinfo, bool *new_var_p)
{
  tree ni = unshare_expr (LOOP_VINFO_NITERS (loop_vinfo));
  if (TREE_CODE (ni) == INTEGER_CST)
    return ni;
  else
    {
      tree ni_name, var;
      gimple_seq stmts = NULL;
      edge pe = loop_preheader_edge (LOOP_VINFO_LOOP (loop_vinfo));

      var = create_tmp_var (TREE_TYPE (ni), "niters");
      ni_name = force_gimple_operand (ni, &stmts, false, var);
      if (stmts)
	{
	  gsi_insert_seq_on_edge_immediate (pe, stmts);
	  if (new_var_p != NULL)
	    *new_var_p = true;
	}

      return ni_name;
    }
}

/* Calculate the number of iterations above which vectorized loop will be
   preferred than scalar loop.  NITERS_PROLOG is the number of iterations
   of prolog loop.  If it's integer const, the integer number is also passed
   in INT_NITERS_PROLOG.  BOUND_PROLOG is the upper bound (inclusive) of the
   number of iterations of the prolog loop.  BOUND_EPILOG is the corresponding
   value for the epilog loop.  If CHECK_PROFITABILITY is true, TH is the
   threshold below which the scalar (rather than vectorized) loop will be
   executed.  This function stores the upper bound (inclusive) of the result
   in BOUND_SCALAR.  */

static tree
vect_gen_scalar_loop_niters (tree niters_prolog, int int_niters_prolog,
			     int bound_prolog, poly_int64 bound_epilog, int th,
			     poly_uint64 *bound_scalar,
			     bool check_profitability)
{
  tree type = TREE_TYPE (niters_prolog);
  tree niters = fold_build2 (PLUS_EXPR, type, niters_prolog,
			     build_int_cst (type, bound_epilog));

  *bound_scalar = bound_prolog + bound_epilog;
  if (check_profitability)
    {
      /* TH indicates the minimum niters of vectorized loop, while we
	 compute the maximum niters of scalar loop.  */
      th--;
      /* Peeling for constant times.  */
      if (int_niters_prolog >= 0)
	{
	  *bound_scalar = upper_bound (int_niters_prolog + bound_epilog, th);
	  return build_int_cst (type, *bound_scalar);
	}
      /* Peeling an unknown number of times.  Note that both BOUND_PROLOG
	 and BOUND_EPILOG are inclusive upper bounds.  */
      if (known_ge (th, bound_prolog + bound_epilog))
	{
	  *bound_scalar = th;
	  return build_int_cst (type, th);
	}
      /* Need to do runtime comparison.  */
      else if (maybe_gt (th, bound_epilog))
	{
	  *bound_scalar = upper_bound (*bound_scalar, th);
	  return fold_build2 (MAX_EXPR, type,
			      build_int_cst (type, th), niters);
	}
    }
  return niters;
}

/* NITERS is the number of times that the original scalar loop executes
   after peeling.  Work out the maximum number of iterations N that can
   be handled by the vectorized form of the loop and then either:

   a) set *STEP_VECTOR_PTR to the vectorization factor and generate:

	niters_vector = N

   b) set *STEP_VECTOR_PTR to one and generate:

        niters_vector = N / vf

   In both cases, store niters_vector in *NITERS_VECTOR_PTR and add
   any new statements on the loop preheader edge.  NITERS_NO_OVERFLOW
   is true if NITERS doesn't overflow (i.e. if NITERS is always nonzero).  */

void
vect_gen_vector_loop_niters (loop_vec_info loop_vinfo, tree niters,
			     tree *niters_vector_ptr, tree *step_vector_ptr,
			     bool niters_no_overflow)
{
  tree ni_minus_gap, var;
  tree niters_vector, step_vector, type = TREE_TYPE (niters);
  poly_uint64 vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
  edge pe = loop_preheader_edge (LOOP_VINFO_LOOP (loop_vinfo));
  tree log_vf = NULL_TREE;

  /* If epilogue loop is required because of data accesses with gaps, we
     subtract one iteration from the total number of iterations here for
     correct calculation of RATIO.  */
  if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
    {
      ni_minus_gap = fold_build2 (MINUS_EXPR, type, niters,
				  build_one_cst (type));
      if (!is_gimple_val (ni_minus_gap))
	{
	  var = create_tmp_var (type, "ni_gap");
	  gimple *stmts = NULL;
	  ni_minus_gap = force_gimple_operand (ni_minus_gap, &stmts,
					       true, var);
	  gsi_insert_seq_on_edge_immediate (pe, stmts);
	}
    }
  else
    ni_minus_gap = niters;

  /* To silence some unexpected warnings, simply initialize to 0. */
  unsigned HOST_WIDE_INT const_vf = 0;
  if (vf.is_constant (&const_vf)
      && !LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
    {
      /* Create: niters >> log2(vf) */
      /* If it's known that niters == number of latch executions + 1 doesn't
	 overflow, we can generate niters >> log2(vf); otherwise we generate
	 (niters - vf) >> log2(vf) + 1 by using the fact that we know ratio
	 will be at least one.  */
      log_vf = build_int_cst (type, exact_log2 (const_vf));
      if (niters_no_overflow)
	niters_vector = fold_build2 (RSHIFT_EXPR, type, ni_minus_gap, log_vf);
      else
	niters_vector
	  = fold_build2 (PLUS_EXPR, type,
			 fold_build2 (RSHIFT_EXPR, type,
				      fold_build2 (MINUS_EXPR, type,
						   ni_minus_gap,
						   build_int_cst (type, vf)),
				      log_vf),
			 build_int_cst (type, 1));
      step_vector = build_one_cst (type);
    }
  else
    {
      niters_vector = ni_minus_gap;
      step_vector = build_int_cst (type, vf);
    }

  if (!is_gimple_val (niters_vector))
    {
      var = create_tmp_var (type, "bnd");
      gimple_seq stmts = NULL;
      niters_vector = force_gimple_operand (niters_vector, &stmts, true, var);
      gsi_insert_seq_on_edge_immediate (pe, stmts);
      /* Peeling algorithm guarantees that vector loop bound is at least ONE,
	 we set range information to make niters analyzer's life easier.
	 Note the number of latch iteration value can be TYPE_MAX_VALUE so
	 we have to represent the vector niter TYPE_MAX_VALUE + 1 >> log_vf.  */
      if (stmts != NULL && log_vf)
	{
	  if (niters_no_overflow)
	    {
	      value_range vr (type,
			      wi::one (TYPE_PRECISION (type)),
			      wi::rshift (wi::max_value (TYPE_PRECISION (type),
							 TYPE_SIGN (type)),
					  exact_log2 (const_vf),
					  TYPE_SIGN (type)));
	      set_range_info (niters_vector, vr);
	    }
	  /* For VF == 1 the vector IV might also overflow so we cannot
	     assert a minimum value of 1.  */
	  else if (const_vf > 1)
	    {
	      value_range vr (type,
			      wi::one (TYPE_PRECISION (type)),
			      wi::rshift (wi::max_value (TYPE_PRECISION (type),
							 TYPE_SIGN (type))
					  - (const_vf - 1),
					  exact_log2 (const_vf), TYPE_SIGN (type))
			      + 1);
	      set_range_info (niters_vector, vr);
	    }
	}
    }
  *niters_vector_ptr = niters_vector;
  *step_vector_ptr = step_vector;

  return;
}

/* Given NITERS_VECTOR which is the number of iterations for vectorized
   loop specified by LOOP_VINFO after vectorization, compute the number
   of iterations before vectorization (niters_vector * vf) and store it
   to NITERS_VECTOR_MULT_VF_PTR.  */

static void
vect_gen_vector_loop_niters_mult_vf (loop_vec_info loop_vinfo,
				     tree niters_vector,
				     tree *niters_vector_mult_vf_ptr)
{
  /* We should be using a step_vector of VF if VF is variable.  */
  int vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo).to_constant ();
  tree type = TREE_TYPE (niters_vector);
  tree log_vf = build_int_cst (type, exact_log2 (vf));
  tree tree_vf = build_int_cst (type, vf);
  basic_block exit_bb = LOOP_VINFO_IV_EXIT (loop_vinfo)->dest;

  gcc_assert (niters_vector_mult_vf_ptr != NULL);
  tree niters_vector_mult_vf = fold_build2 (LSHIFT_EXPR, type,
					    niters_vector, log_vf);

  /* If we've peeled a vector iteration then subtract one full vector
     iteration.  */
  if (LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo))
    niters_vector_mult_vf = fold_build2 (MINUS_EXPR, type,
					 niters_vector_mult_vf, tree_vf);

  if (!is_gimple_val (niters_vector_mult_vf))
    {
      tree var = create_tmp_var (type, "niters_vector_mult_vf");
      gimple_seq stmts = NULL;
      niters_vector_mult_vf = force_gimple_operand (niters_vector_mult_vf,
						    &stmts, true, var);
      gimple_stmt_iterator gsi = gsi_start_bb (exit_bb);
      gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT);
    }
  *niters_vector_mult_vf_ptr = niters_vector_mult_vf;
}

/* Function slpeel_add_loop_guard adds guard skipping from the beginning
   of SKIP_LOOP to the beginning of UPDATE_LOOP.  GUARD_EDGE and MERGE_EDGE
   are two pred edges of the merge point before UPDATE_LOOP.  The two loops
   appear like below:

       guard_bb:
	 if (cond)
	   goto merge_bb;
	 else
	   goto skip_loop;

     skip_loop:
       header_a:
	 i_1 = PHI<i_0, i_2>;
	 ...
	 i_2 = i_1 + 1;
	 if (cond_a)
	   goto latch_a;
	 else
	   goto exit_a;
       latch_a:
	 goto header_a;

       exit_a:
	 i_5 = PHI<i_2>;

       merge_bb:
	 ;; PHI (i_x = PHI<i_0, i_5>) to be created at merge point.

     update_loop:
       header_b:
	 i_3 = PHI<i_5, i_4>;  ;; Use of i_5 to be replaced with i_x.
	 ...
	 i_4 = i_3 + 1;
	 if (cond_b)
	   goto latch_b;
	 else
	   goto exit_bb;
       latch_b:
	 goto header_b;

       exit_bb:

   This function creates PHI nodes at merge_bb and replaces the use of i_5
   in the update_loop's PHI node with the result of new PHI result.  */

static void
slpeel_update_phi_nodes_for_guard1 (class loop *skip_loop,
				    class loop *update_loop,
				    edge guard_edge, edge merge_edge)
{
  location_t merge_loc, guard_loc;
  edge orig_e = loop_preheader_edge (skip_loop);
  edge update_e = loop_preheader_edge (update_loop);
  gphi_iterator gsi_orig, gsi_update;

  for ((gsi_orig = gsi_start_phis (skip_loop->header),
	gsi_update = gsi_start_phis (update_loop->header));
       !gsi_end_p (gsi_orig) && !gsi_end_p (gsi_update);
       gsi_next (&gsi_orig), gsi_next (&gsi_update))
    {
      gphi *orig_phi = gsi_orig.phi ();
      gphi *update_phi = gsi_update.phi ();

      /* Generate new phi node at merge bb of the guard.  */
      tree new_res = copy_ssa_name (PHI_RESULT (orig_phi));
      gphi *new_phi = create_phi_node (new_res, guard_edge->dest);

      /* Merge bb has two incoming edges: GUARD_EDGE and MERGE_EDGE.  Set the
	 args in NEW_PHI for these edges.  */
      tree merge_arg = PHI_ARG_DEF_FROM_EDGE (update_phi, update_e);
      tree guard_arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, orig_e);
      merge_loc = gimple_phi_arg_location_from_edge (update_phi, update_e);
      guard_loc = gimple_phi_arg_location_from_edge (orig_phi, orig_e);
      add_phi_arg (new_phi, merge_arg, merge_edge, merge_loc);
      add_phi_arg (new_phi, guard_arg, guard_edge, guard_loc);

      /* Update phi in UPDATE_PHI.  */
      adjust_phi_and_debug_stmts (update_phi, update_e, new_res);
    }
}

/* LOOP_VINFO is an epilogue loop whose corresponding main loop can be skipped.
   Return a value that equals:

   - MAIN_LOOP_VALUE when LOOP_VINFO is entered from the main loop and
   - SKIP_VALUE when the main loop is skipped.  */

tree
vect_get_main_loop_result (loop_vec_info loop_vinfo, tree main_loop_value,
			   tree skip_value)
{
  gcc_assert (loop_vinfo->main_loop_edge);

  tree phi_result = make_ssa_name (TREE_TYPE (main_loop_value));
  basic_block bb = loop_vinfo->main_loop_edge->dest;
  gphi *new_phi = create_phi_node (phi_result, bb);
  add_phi_arg (new_phi, main_loop_value, loop_vinfo->main_loop_edge,
	       UNKNOWN_LOCATION);
  add_phi_arg (new_phi, skip_value,
	       loop_vinfo->skip_main_loop_edge, UNKNOWN_LOCATION);
  return phi_result;
}

/* Function vect_do_peeling.

   Input:
   - LOOP_VINFO: Represent a loop to be vectorized, which looks like:

       preheader:
     LOOP:
       header_bb:
	 loop_body
	 if (exit_loop_cond) goto exit_bb
	 else                goto header_bb
       exit_bb:

   - NITERS: The number of iterations of the loop.
   - NITERSM1: The number of iterations of the loop's latch.
   - NITERS_NO_OVERFLOW: No overflow in computing NITERS.
   - TH, CHECK_PROFITABILITY: Threshold of niters to vectorize loop if
			      CHECK_PROFITABILITY is true.
   Output:
   - *NITERS_VECTOR and *STEP_VECTOR describe how the main loop should
     iterate after vectorization; see vect_set_loop_condition for details.
   - *NITERS_VECTOR_MULT_VF_VAR is either null or an SSA name that
     should be set to the number of scalar iterations handled by the
     vector loop.  The SSA name is only used on exit from the loop.

   This function peels prolog and epilog from the loop, adds guards skipping
   PROLOG and EPILOG for various conditions.  As a result, the changed CFG
   would look like:

       guard_bb_1:
	 if (prefer_scalar_loop) goto merge_bb_1
	 else                    goto guard_bb_2

       guard_bb_2:
         if (skip_prolog) goto merge_bb_2
         else             goto prolog_preheader

       prolog_preheader:
     PROLOG:
       prolog_header_bb:
	 prolog_body
	 if (exit_prolog_cond) goto prolog_exit_bb
	 else                  goto prolog_header_bb
       prolog_exit_bb:

       merge_bb_2:

       vector_preheader:
     VECTOR LOOP:
       vector_header_bb:
	 vector_body
	 if (exit_vector_cond) goto vector_exit_bb
	 else                  goto vector_header_bb
       vector_exit_bb:

       guard_bb_3:
	 if (skip_epilog) goto merge_bb_3
	 else             goto epilog_preheader

       merge_bb_1:

       epilog_preheader:
     EPILOG:
       epilog_header_bb:
	 epilog_body
	 if (exit_epilog_cond) goto merge_bb_3
	 else                  goto epilog_header_bb

       merge_bb_3:

   Note this function peels prolog and epilog only if it's necessary,
   as well as guards.
   This function returns the epilogue loop if a decision was made to vectorize
   it, otherwise NULL.

   The analysis resulting in this epilogue loop's loop_vec_info was performed
   in the same vect_analyze_loop call as the main loop's.  At that time
   vect_analyze_loop constructs a list of accepted loop_vec_info's for lower
   vectorization factors than the main loop.  This list is stored in the main
   loop's loop_vec_info in the 'epilogue_vinfos' member.  Everytime we decide to
   vectorize the epilogue loop for a lower vectorization factor,  the
   loop_vec_info sitting at the top of the epilogue_vinfos list is removed,
   updated and linked to the epilogue loop.  This is later used to vectorize
   the epilogue.  The reason the loop_vec_info needs updating is that it was
   constructed based on the original main loop, and the epilogue loop is a
   copy of this loop, so all links pointing to statements in the original loop
   need updating.  Furthermore, these loop_vec_infos share the
   data_reference's records, which will also need to be updated.

   TODO: Guard for prefer_scalar_loop should be emitted along with
   versioning conditions if loop versioning is needed.  */


class loop *
vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
		 tree *niters_vector, tree *step_vector,
		 tree *niters_vector_mult_vf_var, int th,
		 bool check_profitability, bool niters_no_overflow,
		 tree *advance)
{
  edge e, guard_e;
  tree type = TREE_TYPE (niters), guard_cond;
  basic_block guard_bb, guard_to;
  profile_probability prob_prolog, prob_vector, prob_epilog;
  int estimated_vf;
  int prolog_peeling = 0;
  bool vect_epilogues = loop_vinfo->epilogue_vinfos.length () > 0;
  /* We currently do not support prolog peeling if the target alignment is not
     known at compile time.  'vect_gen_prolog_loop_niters' depends on the
     target alignment being constant.  */
  dr_vec_info *dr_info = LOOP_VINFO_UNALIGNED_DR (loop_vinfo);
  if (dr_info && !DR_TARGET_ALIGNMENT (dr_info).is_constant ())
    return NULL;

  if (!vect_use_loop_mask_for_alignment_p (loop_vinfo))
    prolog_peeling = LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo);

  poly_uint64 vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
  poly_uint64 bound_epilog = 0;
  if (!LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
      && LOOP_VINFO_PEELING_FOR_NITER (loop_vinfo))
    bound_epilog += vf - 1;
  if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo))
    bound_epilog += 1;

  /* For early breaks the scalar loop needs to execute at most VF times
     to find the element that caused the break.  */
  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
    bound_epilog = vf;

  bool epilog_peeling = maybe_ne (bound_epilog, 0U);
  poly_uint64 bound_scalar = bound_epilog;

  if (!prolog_peeling && !epilog_peeling)
    return NULL;

  /* Before doing any peeling make sure to reset debug binds outside of
     the loop refering to defs not in LC SSA.  */
  class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
  for (unsigned i = 0; i < loop->num_nodes; ++i)
    {
      basic_block bb = LOOP_VINFO_BBS (loop_vinfo)[i];
      imm_use_iterator ui;
      gimple *use_stmt;
      for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
	   gsi_next (&gsi))
	{
	  FOR_EACH_IMM_USE_STMT (use_stmt, ui, gimple_phi_result (gsi.phi ()))
	    if (gimple_debug_bind_p (use_stmt)
		&& loop != gimple_bb (use_stmt)->loop_father
		&& !flow_loop_nested_p (loop,
					gimple_bb (use_stmt)->loop_father))
	      {
		gimple_debug_bind_reset_value (use_stmt);
		update_stmt (use_stmt);
	      }
	}
      for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
	   gsi_next (&gsi))
	{
	  ssa_op_iter op_iter;
	  def_operand_p def_p;
	  FOR_EACH_SSA_DEF_OPERAND (def_p, gsi_stmt (gsi), op_iter, SSA_OP_DEF)
	    FOR_EACH_IMM_USE_STMT (use_stmt, ui, DEF_FROM_PTR (def_p))
	      if (gimple_debug_bind_p (use_stmt)
		  && loop != gimple_bb (use_stmt)->loop_father
		  && !flow_loop_nested_p (loop,
					  gimple_bb (use_stmt)->loop_father))
		{
		  gimple_debug_bind_reset_value (use_stmt);
		  update_stmt (use_stmt);
		}
	}
    }

  prob_vector = profile_probability::guessed_always ().apply_scale (9, 10);
  estimated_vf = vect_vf_for_cost (loop_vinfo);
  if (estimated_vf == 2)
    estimated_vf = 3;
  prob_prolog = prob_epilog = profile_probability::guessed_always ()
			.apply_scale (estimated_vf - 1, estimated_vf);

  class loop *prolog, *epilog = NULL;
  class loop *first_loop = loop;
  bool irred_flag = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP;

  /* SSA form needs to be up-to-date since we are going to manually
     update SSA form in slpeel_tree_duplicate_loop_to_edge_cfg and delete all
     update SSA state after that, so we have to make sure to not lose any
     pending update needs.  */
  gcc_assert (!need_ssa_update_p (cfun));

  /* If we're vectorizing an epilogue loop, we have ensured that the
     virtual operand is in SSA form throughout the vectorized main loop.
     Normally it is possible to trace the updated
     vector-stmt vdefs back to scalar-stmt vdefs and vector-stmt vuses
     back to scalar-stmt vuses, meaning that the effect of the SSA update
     remains local to the main loop.  However, there are rare cases in
     which the vectorized loop should have vdefs even when the original scalar
     loop didn't.  For example, vectorizing a load with IFN_LOAD_LANES
     introduces clobbers of the temporary vector array, which in turn
     needs new vdefs.  If the scalar loop doesn't write to memory, these
     new vdefs will be the only ones in the vector loop.
     We are currently defering updating virtual SSA form and creating
     of a virtual PHI for this case so we do not have to make sure the
     newly introduced virtual def is in LCSSA form.  */

  if (MAY_HAVE_DEBUG_BIND_STMTS)
    {
      gcc_assert (!adjust_vec.exists ());
      adjust_vec.create (32);
    }
  initialize_original_copy_tables ();

  /* Record the anchor bb at which the guard should be placed if the scalar
     loop might be preferred.  */
  basic_block anchor = loop_preheader_edge (loop)->src;

  /* Generate the number of iterations for the prolog loop.  We do this here
     so that we can also get the upper bound on the number of iterations.  */
  tree niters_prolog;
  int bound_prolog = 0;
  if (prolog_peeling)
    {
      niters_prolog = vect_gen_prolog_loop_niters (loop_vinfo, anchor,
						    &bound_prolog);
      /* If algonment peeling is known, we will always execute prolog.  */
      if (TREE_CODE (niters_prolog) == INTEGER_CST)
	prob_prolog = profile_probability::always ();
    }
  else
    niters_prolog = build_int_cst (type, 0);

  loop_vec_info epilogue_vinfo = NULL;
  if (vect_epilogues)
    {
      epilogue_vinfo = loop_vinfo->epilogue_vinfos[0];
      loop_vinfo->epilogue_vinfos.ordered_remove (0);
    }

  tree niters_vector_mult_vf = NULL_TREE;
  /* Saving NITERs before the loop, as this may be changed by prologue.  */
  tree before_loop_niters = LOOP_VINFO_NITERS (loop_vinfo);
  edge update_e = NULL, skip_e = NULL;
  unsigned int lowest_vf = constant_lower_bound (vf);
  /* Prolog loop may be skipped.  */
  bool skip_prolog = (prolog_peeling != 0);
  /* Skip this loop to epilog when there are not enough iterations to enter this
     vectorized loop.  If true we should perform runtime checks on the NITERS
     to check whether we should skip the current vectorized loop.  If we know
     the number of scalar iterations we may choose to add a runtime check if
     this number "maybe" smaller than the number of iterations required
     when we know the number of scalar iterations may potentially
     be smaller than the number of iterations required to enter this loop, for
     this we use the upper bounds on the prolog and epilog peeling.  When we
     don't know the number of iterations and don't require versioning it is
     because we have asserted that there are enough scalar iterations to enter
     the main loop, so this skip is not necessary.  When we are versioning then
     we only add such a skip if we have chosen to vectorize the epilogue.  */
  bool skip_vector = (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
		      ? maybe_lt (LOOP_VINFO_INT_NITERS (loop_vinfo),
				  bound_prolog + bound_epilog)
		      : (!LOOP_REQUIRES_VERSIONING (loop_vinfo)
			 || vect_epilogues));

  /* Epilog loop must be executed if the number of iterations for epilog
     loop is known at compile time, otherwise we need to add a check at
     the end of vector loop and skip to the end of epilog loop.  */
  bool skip_epilog = (prolog_peeling < 0
		      || !LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
		      || !vf.is_constant ());
  /* PEELING_FOR_GAPS and peeling for early breaks are special because epilog
     loop must be executed.  */
  if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
      || LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
    skip_epilog = false;

  class loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
  auto_vec<profile_count> original_counts;
  basic_block *original_bbs = NULL;

  if (skip_vector)
    {
      split_edge (loop_preheader_edge (loop));

      if (epilog_peeling && (vect_epilogues || scalar_loop == NULL))
	{
	  original_bbs = get_loop_body (loop);
	  for (unsigned int i = 0; i < loop->num_nodes; i++)
	    original_counts.safe_push(original_bbs[i]->count);
	}

      /* Due to the order in which we peel prolog and epilog, we first
	 propagate probability to the whole loop.  The purpose is to
	 avoid adjusting probabilities of both prolog and vector loops
	 separately.  Note in this case, the probability of epilog loop
	 needs to be scaled back later.  */
      basic_block bb_before_loop = loop_preheader_edge (loop)->src;
      if (prob_vector.initialized_p ())
	{
	  scale_bbs_frequencies (&bb_before_loop, 1, prob_vector);
	  scale_loop_profile (loop, prob_vector, -1);
	}
    }

  if (vect_epilogues)
    {
      /* Make sure to set the epilogue's epilogue scalar loop, such that we can
	 use the original scalar loop as remaining epilogue if necessary.  */
      LOOP_VINFO_SCALAR_LOOP (epilogue_vinfo)
	= LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
      LOOP_VINFO_SCALAR_IV_EXIT (epilogue_vinfo)
	= LOOP_VINFO_SCALAR_IV_EXIT (loop_vinfo);
    }

  if (prolog_peeling)
    {
      e = loop_preheader_edge (loop);
      edge exit_e = LOOP_VINFO_IV_EXIT (loop_vinfo);
      gcc_checking_assert (slpeel_can_duplicate_loop_p (loop, exit_e, e)
			   && !LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo));

      /* Peel prolog and put it on preheader edge of loop.  */
      edge scalar_e = LOOP_VINFO_SCALAR_IV_EXIT (loop_vinfo);
      edge prolog_e = NULL;
      prolog = slpeel_tree_duplicate_loop_to_edge_cfg (loop, exit_e,
						       scalar_loop, scalar_e,
						       e, &prolog_e);
      gcc_assert (prolog);
      prolog->force_vectorize = false;

      first_loop = prolog;
      reset_original_copy_tables ();

      /* Update the number of iterations for prolog loop.  */
      tree step_prolog = build_one_cst (TREE_TYPE (niters_prolog));
      vect_set_loop_condition (prolog, prolog_e, NULL, niters_prolog,
			       step_prolog, NULL_TREE, false);

      /* Skip the prolog loop.  */
      if (skip_prolog)
	{
	  guard_cond = fold_build2 (EQ_EXPR, boolean_type_node,
				    niters_prolog, build_int_cst (type, 0));
	  guard_bb = loop_preheader_edge (prolog)->src;
	  basic_block bb_after_prolog = loop_preheader_edge (loop)->src;
	  guard_to = split_edge (loop_preheader_edge (loop));
	  guard_e = slpeel_add_loop_guard (guard_bb, guard_cond,
					   guard_to, guard_bb,
					   prob_prolog.invert (),
					   irred_flag);
	  for (edge alt_e : get_loop_exit_edges (prolog))
	    {
	      if (alt_e == prolog_e)
		continue;
	      basic_block old_dom
		= get_immediate_dominator (CDI_DOMINATORS, alt_e->dest);
	      if (flow_bb_inside_loop_p (prolog, old_dom))
		{
		  auto_vec<basic_block, 8> queue;
		  for (auto son = first_dom_son (CDI_DOMINATORS, old_dom);
		       son; son = next_dom_son (CDI_DOMINATORS, son))
		    if (!flow_bb_inside_loop_p (prolog, son))
		      queue.safe_push (son);
		  for (auto son : queue)
		    set_immediate_dominator (CDI_DOMINATORS, son, guard_bb);
		}
	    }

	  e = EDGE_PRED (guard_to, 0);
	  e = (e != guard_e ? e : EDGE_PRED (guard_to, 1));
	  slpeel_update_phi_nodes_for_guard1 (prolog, loop, guard_e, e);

	  scale_bbs_frequencies (&bb_after_prolog, 1, prob_prolog);
	  scale_loop_profile (prolog, prob_prolog, bound_prolog - 1);
	}

      /* Update init address of DRs.  */
      vect_update_inits_of_drs (loop_vinfo, niters_prolog, PLUS_EXPR);
      /* Update niters for vector loop.  */
      LOOP_VINFO_NITERS (loop_vinfo)
	= fold_build2 (MINUS_EXPR, type, niters, niters_prolog);
      LOOP_VINFO_NITERSM1 (loop_vinfo)
	= fold_build2 (MINUS_EXPR, type,
		       LOOP_VINFO_NITERSM1 (loop_vinfo), niters_prolog);
      bool new_var_p = false;
      niters = vect_build_loop_niters (loop_vinfo, &new_var_p);
      /* It's guaranteed that vector loop bound before vectorization is at
	 least VF, so set range information for newly generated var.  */
      if (new_var_p)
	{
	  value_range vr (type,
			  wi::to_wide (build_int_cst (type, lowest_vf)),
			  wi::to_wide (TYPE_MAX_VALUE (type)));
	  set_range_info (niters, vr);
	}

      /* Prolog iterates at most bound_prolog times, latch iterates at
	 most bound_prolog - 1 times.  */
      record_niter_bound (prolog, bound_prolog - 1, false, true);
      delete_update_ssa ();
      adjust_vec_debug_stmts ();
      scev_reset ();
    }
  basic_block bb_before_epilog = NULL;

  if (epilog_peeling)
    {
      e = LOOP_VINFO_IV_EXIT (loop_vinfo);
      gcc_checking_assert (slpeel_can_duplicate_loop_p (loop, e, e));

      /* Peel epilog and put it on exit edge of loop.  If we are vectorizing
	 said epilog then we should use a copy of the main loop as a starting
	 point.  This loop may have already had some preliminary transformations
	 to allow for more optimal vectorization, for example if-conversion.
	 If we are not vectorizing the epilog then we should use the scalar loop
	 as the transformations mentioned above make less or no sense when not
	 vectorizing.  */
      edge scalar_e = LOOP_VINFO_SCALAR_IV_EXIT (loop_vinfo);
      epilog = vect_epilogues ? get_loop_copy (loop) : scalar_loop;
      edge epilog_e = vect_epilogues ? e : scalar_e;
      edge new_epilog_e = NULL;
      auto_vec<basic_block> doms;
      epilog
	= slpeel_tree_duplicate_loop_to_edge_cfg (loop, e, epilog, epilog_e, e,
						  &new_epilog_e, true, &doms);

      LOOP_VINFO_EPILOGUE_IV_EXIT (loop_vinfo) = new_epilog_e;
      gcc_assert (epilog);
      gcc_assert (new_epilog_e);
      epilog->force_vectorize = false;
      bb_before_epilog = loop_preheader_edge (epilog)->src;

      /* Scalar version loop may be preferred.  In this case, add guard
	 and skip to epilog.  Note this only happens when the number of
	 iterations of loop is unknown at compile time, otherwise this
	 won't be vectorized.  */
      if (skip_vector)
	{
	  /* Additional epilogue iteration is peeled if gap exists.  */
	  tree t = vect_gen_scalar_loop_niters (niters_prolog, prolog_peeling,
						bound_prolog, bound_epilog,
						th, &bound_scalar,
						check_profitability);
	  /* Build guard against NITERSM1 since NITERS may overflow.  */
	  guard_cond = fold_build2 (LT_EXPR, boolean_type_node, nitersm1, t);
	  guard_bb = anchor;
	  guard_to = split_edge (loop_preheader_edge (epilog));
	  guard_e = slpeel_add_loop_guard (guard_bb, guard_cond,
					   guard_to, guard_bb,
					   prob_vector.invert (),
					   irred_flag);
	  skip_e = guard_e;
	  e = EDGE_PRED (guard_to, 0);
	  e = (e != guard_e ? e : EDGE_PRED (guard_to, 1));
	  slpeel_update_phi_nodes_for_guard1 (first_loop, epilog, guard_e, e);

	  /* Simply propagate profile info from guard_bb to guard_to which is
	     a merge point of control flow.  */
	  profile_count old_count = guard_to->count;
	  guard_to->count = guard_bb->count;

	  /* Restore the counts of the epilog loop if we didn't use the scalar loop. */
	  if (vect_epilogues || scalar_loop == NULL)
	    {
	      gcc_assert(epilog->num_nodes == loop->num_nodes);
	      basic_block *bbs = get_loop_body (epilog);
	      for (unsigned int i = 0; i < epilog->num_nodes; i++)
		{
		  gcc_assert(get_bb_original (bbs[i]) == original_bbs[i]);
		  bbs[i]->count = original_counts[i];
		}
	      free (bbs);
	      free (original_bbs);
	    }
	  else if (old_count.nonzero_p ())
	    scale_loop_profile (epilog, guard_to->count.probability_in (old_count), -1);

	  /* Only need to handle basic block before epilog loop if it's not
	     the guard_bb, which is the case when skip_vector is true.  */
	  if (guard_bb != bb_before_epilog && single_pred_p (bb_before_epilog))
	    bb_before_epilog->count = single_pred_edge (bb_before_epilog)->count ();
	  bb_before_epilog = loop_preheader_edge (epilog)->src;
	}

      /* If loop is peeled for non-zero constant times, now niters refers to
	 orig_niters - prolog_peeling, it won't overflow even the orig_niters
	 overflows.  */
      niters_no_overflow |= (prolog_peeling > 0);
      vect_gen_vector_loop_niters (loop_vinfo, niters,
				   niters_vector, step_vector,
				   niters_no_overflow);
      if (!integer_onep (*step_vector))
	{
	  /* On exit from the loop we will have an easy way of calcalating
	     NITERS_VECTOR / STEP * STEP.  Install a dummy definition
	     until then.  */
	  niters_vector_mult_vf = make_ssa_name (TREE_TYPE (*niters_vector));
	  SSA_NAME_DEF_STMT (niters_vector_mult_vf) = gimple_build_nop ();
	  *niters_vector_mult_vf_var = niters_vector_mult_vf;
	}
      else
	vect_gen_vector_loop_niters_mult_vf (loop_vinfo, *niters_vector,
					     &niters_vector_mult_vf);
      /* Update IVs of original loop as if they were advanced by
	 niters_vector_mult_vf steps.  */
      gcc_checking_assert (vect_can_advance_ivs_p (loop_vinfo));
      update_e = skip_vector ? e : loop_preheader_edge (epilog);
      if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
	update_e = single_succ_edge (LOOP_VINFO_IV_EXIT (loop_vinfo)->dest);

      /* If we have a peeled vector iteration, all exits are the same, leave it
	 and so the main exit needs to be treated the same as the alternative
	 exits in that we leave their updates to vectorizable_live_operations.
	 */
      if (!LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo))
	vect_update_ivs_after_vectorizer (loop_vinfo, niters_vector_mult_vf,
					  update_e);

      /* If we have a peeled vector iteration we will never skip the epilog loop
	 and we can simplify the cfg a lot by not doing the edge split.  */
      if (skip_epilog || LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
	{
	  guard_cond = fold_build2 (EQ_EXPR, boolean_type_node,
				    niters, niters_vector_mult_vf);

	  guard_bb = LOOP_VINFO_IV_EXIT (loop_vinfo)->dest;
	  edge epilog_e = LOOP_VINFO_EPILOGUE_IV_EXIT (loop_vinfo);
	  guard_to = epilog_e->dest;
	  guard_e = slpeel_add_loop_guard (guard_bb, guard_cond, guard_to,
					   skip_vector ? anchor : guard_bb,
					   prob_epilog.invert (),
					   irred_flag);
	  doms.safe_push (guard_to);
	  if (vect_epilogues)
	    epilogue_vinfo->skip_this_loop_edge = guard_e;
	  edge main_iv = LOOP_VINFO_IV_EXIT (loop_vinfo);
	  gphi_iterator gsi2 = gsi_start_phis (main_iv->dest);
	  for (gphi_iterator gsi = gsi_start_phis (guard_to);
	       !gsi_end_p (gsi); gsi_next (&gsi))
	    {
	      /* We are expecting all of the PHIs we have on epilog_e
		 to be also on the main loop exit.  But sometimes
		 a stray virtual definition can appear at epilog_e
		 which we can then take as the same on all exits,
		 we've removed the LC SSA PHI on the main exit before
		 so we wouldn't need to create a loop PHI for it.  */
	      if (virtual_operand_p (gimple_phi_result (*gsi))
		  && (gsi_end_p (gsi2)
		      || !virtual_operand_p (gimple_phi_result (*gsi2))))
		add_phi_arg (*gsi,
			     gimple_phi_arg_def_from_edge (*gsi, epilog_e),
			     guard_e, UNKNOWN_LOCATION);
	      else
		{
		  add_phi_arg (*gsi, gimple_phi_result (*gsi2), guard_e,
			       UNKNOWN_LOCATION);
		  gsi_next (&gsi2);
		}
	    }

	  /* Only need to handle basic block before epilog loop if it's not
	     the guard_bb, which is the case when skip_vector is true.  */
	  if (guard_bb != bb_before_epilog)
	    {
	      prob_epilog = prob_vector * prob_epilog + prob_vector.invert ();

	      scale_bbs_frequencies (&bb_before_epilog, 1, prob_epilog);
	    }
	  scale_loop_profile (epilog, prob_epilog, -1);
	}

      /* Recalculate the dominators after adding the guard edge.  */
      if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
	iterate_fix_dominators (CDI_DOMINATORS, doms, false);

      /* When we do not have a loop-around edge to the epilog we know
	 the vector loop covered at least VF scalar iterations unless
	 we have early breaks.
	 Update any known upper bound with this knowledge.  */
      if (! skip_vector
	  && ! LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
	{
	  if (epilog->any_upper_bound)
	    epilog->nb_iterations_upper_bound -= lowest_vf;
	  if (epilog->any_likely_upper_bound)
	    epilog->nb_iterations_likely_upper_bound -= lowest_vf;
	  if (epilog->any_estimate)
	    epilog->nb_iterations_estimate -= lowest_vf;
	}

      unsigned HOST_WIDE_INT bound;
      if (bound_scalar.is_constant (&bound))
	{
	  gcc_assert (bound != 0);
	  /* Adjust the upper bound by the extra peeled vector iteration if we
	     are an epilogue of an peeled vect loop and not VLA.  For VLA the
	     loop bounds are unknown.  */
	  if (LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo)
	      && vf.is_constant ())
	    bound += vf.to_constant ();
	  /* -1 to convert loop iterations to latch iterations.  */
	  record_niter_bound (epilog, bound - 1, false, true);
	  scale_loop_profile (epilog, profile_probability::always (),
			      bound - 1);
	}

      delete_update_ssa ();
      adjust_vec_debug_stmts ();
      scev_reset ();
    }

  if (vect_epilogues)
    {
      epilog->aux = epilogue_vinfo;
      LOOP_VINFO_LOOP (epilogue_vinfo) = epilog;
      LOOP_VINFO_IV_EXIT (epilogue_vinfo)
	= LOOP_VINFO_EPILOGUE_IV_EXIT (loop_vinfo);

      loop_constraint_clear (epilog, LOOP_C_INFINITE);

      /* We now must calculate the number of NITERS performed by the previous
	 loop and EPILOGUE_NITERS to be performed by the epilogue.  */
      tree niters = fold_build2 (PLUS_EXPR, TREE_TYPE (niters_vector_mult_vf),
				 niters_prolog, niters_vector_mult_vf);

      /* If skip_vector we may skip the previous loop, we insert a phi-node to
	 determine whether we are coming from the previous vectorized loop
	 using the update_e edge or the skip_vector basic block using the
	 skip_e edge.  */
      if (skip_vector)
	{
	  gcc_assert (update_e != NULL && skip_e != NULL);
	  gphi *new_phi = create_phi_node (make_ssa_name (TREE_TYPE (niters)),
					   update_e->dest);
	  tree new_ssa = make_ssa_name (TREE_TYPE (niters));
	  gimple *stmt = gimple_build_assign (new_ssa, niters);
	  gimple_stmt_iterator gsi;
	  if (TREE_CODE (niters_vector_mult_vf) == SSA_NAME
	      && SSA_NAME_DEF_STMT (niters_vector_mult_vf)->bb != NULL)
	    {
	      gsi = gsi_for_stmt (SSA_NAME_DEF_STMT (niters_vector_mult_vf));
	      gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
	    }
	  else
	    {
	      gsi = gsi_last_bb (update_e->src);
	      gsi_insert_before (&gsi, stmt, GSI_NEW_STMT);
	    }

	  niters = new_ssa;
	  add_phi_arg (new_phi, niters, update_e, UNKNOWN_LOCATION);
	  add_phi_arg (new_phi, build_zero_cst (TREE_TYPE (niters)), skip_e,
		       UNKNOWN_LOCATION);
	  niters = PHI_RESULT (new_phi);
	  epilogue_vinfo->main_loop_edge = update_e;
	  epilogue_vinfo->skip_main_loop_edge = skip_e;
	}

      /* Set ADVANCE to the number of iterations performed by the previous
	 loop and its prologue.  */
      *advance = niters;

      /* Subtract the number of iterations performed by the vectorized loop
	 from the number of total iterations.  */
      tree epilogue_niters = fold_build2 (MINUS_EXPR, TREE_TYPE (niters),
					  before_loop_niters,
					  niters);

      LOOP_VINFO_NITERS (epilogue_vinfo) = epilogue_niters;
      LOOP_VINFO_NITERSM1 (epilogue_vinfo)
	= fold_build2 (MINUS_EXPR, TREE_TYPE (epilogue_niters),
		       epilogue_niters,
		       build_one_cst (TREE_TYPE (epilogue_niters)));

      /* Decide what to do if the number of epilogue iterations is not
	 a multiple of the epilogue loop's vectorization factor.
	 We should have rejected the loop during the analysis phase
	 if this fails.  */
      bool res = vect_determine_partial_vectors_and_peeling (epilogue_vinfo);
      gcc_assert (res);
    }

  adjust_vec.release ();
  free_original_copy_tables ();

  return vect_epilogues ? epilog : NULL;
}

/* Function vect_create_cond_for_niters_checks.

   Create a conditional expression that represents the run-time checks for
   loop's niter.  The loop is guaranteed to terminate if the run-time
   checks hold.

   Input:
   COND_EXPR  - input conditional expression.  New conditions will be chained
		with logical AND operation.  If it is NULL, then the function
		is used to return the number of alias checks.
   LOOP_VINFO - field LOOP_VINFO_MAY_ALIAS_STMTS contains the list of ddrs
		to be checked.

   Output:
   COND_EXPR - conditional expression.

   The returned COND_EXPR is the conditional expression to be used in the
   if statement that controls which version of the loop gets executed at
   runtime.  */

static void
vect_create_cond_for_niters_checks (loop_vec_info loop_vinfo, tree *cond_expr)
{
  tree part_cond_expr = LOOP_VINFO_NITERS_ASSUMPTIONS (loop_vinfo);

  if (*cond_expr)
    *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
			      *cond_expr, part_cond_expr);
  else
    *cond_expr = part_cond_expr;
}

/* Set *COND_EXPR to a tree that is true when both the original *COND_EXPR
   and PART_COND_EXPR are true.  Treat a null *COND_EXPR as "true".  */

static void
chain_cond_expr (tree *cond_expr, tree part_cond_expr)
{
  if (*cond_expr)
    *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
			      *cond_expr, part_cond_expr);
  else
    *cond_expr = part_cond_expr;
}

/* Function vect_create_cond_for_align_checks.

   Create a conditional expression that represents the alignment checks for
   all of data references (array element references) whose alignment must be
   checked at runtime.

   Input:
   COND_EXPR  - input conditional expression.  New conditions will be chained
                with logical AND operation.
   LOOP_VINFO - two fields of the loop information are used.
                LOOP_VINFO_PTR_MASK is the mask used to check the alignment.
                LOOP_VINFO_MAY_MISALIGN_STMTS contains the refs to be checked.

   Output:
   COND_EXPR_STMT_LIST - statements needed to construct the conditional
                         expression.
   The returned value is the conditional expression to be used in the if
   statement that controls which version of the loop gets executed at runtime.

   The algorithm makes two assumptions:
     1) The number of bytes "n" in a vector is a power of 2.
     2) An address "a" is aligned if a%n is zero and that this
        test can be done as a&(n-1) == 0.  For example, for 16
        byte vectors the test is a&0xf == 0.  */

static void
vect_create_cond_for_align_checks (loop_vec_info loop_vinfo,
                                   tree *cond_expr,
				   gimple_seq *cond_expr_stmt_list)
{
  const vec<stmt_vec_info> &may_misalign_stmts
    = LOOP_VINFO_MAY_MISALIGN_STMTS (loop_vinfo);
  stmt_vec_info stmt_info;
  int mask = LOOP_VINFO_PTR_MASK (loop_vinfo);
  tree mask_cst;
  unsigned int i;
  tree int_ptrsize_type;
  char tmp_name[20];
  tree or_tmp_name = NULL_TREE;
  tree and_tmp_name;
  gimple *and_stmt;
  tree ptrsize_zero;
  tree part_cond_expr;

  /* Check that mask is one less than a power of 2, i.e., mask is
     all zeros followed by all ones.  */
  gcc_assert ((mask != 0) && ((mask & (mask+1)) == 0));

  int_ptrsize_type = signed_type_for (ptr_type_node);

  /* Create expression (mask & (dr_1 || ... || dr_n)) where dr_i is the address
     of the first vector of the i'th data reference. */

  FOR_EACH_VEC_ELT (may_misalign_stmts, i, stmt_info)
    {
      gimple_seq new_stmt_list = NULL;
      tree addr_base;
      tree addr_tmp_name;
      tree new_or_tmp_name;
      gimple *addr_stmt, *or_stmt;
      tree vectype = STMT_VINFO_VECTYPE (stmt_info);
      bool negative = tree_int_cst_compare
	(DR_STEP (STMT_VINFO_DATA_REF (stmt_info)), size_zero_node) < 0;
      tree offset = negative
	? size_int ((-TYPE_VECTOR_SUBPARTS (vectype) + 1)
		    * TREE_INT_CST_LOW (TYPE_SIZE_UNIT (TREE_TYPE (vectype))))
	: size_zero_node;

      /* create: addr_tmp = (int)(address_of_first_vector) */
      addr_base =
	vect_create_addr_base_for_vector_ref (loop_vinfo,
					      stmt_info, &new_stmt_list,
					      offset);
      if (new_stmt_list != NULL)
	gimple_seq_add_seq (cond_expr_stmt_list, new_stmt_list);

      sprintf (tmp_name, "addr2int%d", i);
      addr_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, tmp_name);
      addr_stmt = gimple_build_assign (addr_tmp_name, NOP_EXPR, addr_base);
      gimple_seq_add_stmt (cond_expr_stmt_list, addr_stmt);

      /* The addresses are OR together.  */

      if (or_tmp_name != NULL_TREE)
        {
          /* create: or_tmp = or_tmp | addr_tmp */
          sprintf (tmp_name, "orptrs%d", i);
	  new_or_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, tmp_name);
	  or_stmt = gimple_build_assign (new_or_tmp_name, BIT_IOR_EXPR,
					 or_tmp_name, addr_tmp_name);
	  gimple_seq_add_stmt (cond_expr_stmt_list, or_stmt);
          or_tmp_name = new_or_tmp_name;
        }
      else
        or_tmp_name = addr_tmp_name;

    } /* end for i */

  mask_cst = build_int_cst (int_ptrsize_type, mask);

  /* create: and_tmp = or_tmp & mask  */
  and_tmp_name = make_temp_ssa_name (int_ptrsize_type, NULL, "andmask");

  and_stmt = gimple_build_assign (and_tmp_name, BIT_AND_EXPR,
				  or_tmp_name, mask_cst);
  gimple_seq_add_stmt (cond_expr_stmt_list, and_stmt);

  /* Make and_tmp the left operand of the conditional test against zero.
     if and_tmp has a nonzero bit then some address is unaligned.  */
  ptrsize_zero = build_int_cst (int_ptrsize_type, 0);
  part_cond_expr = fold_build2 (EQ_EXPR, boolean_type_node,
				and_tmp_name, ptrsize_zero);
  chain_cond_expr (cond_expr, part_cond_expr);
}

/* If LOOP_VINFO_CHECK_UNEQUAL_ADDRS contains <A1, B1>, ..., <An, Bn>,
   create a tree representation of: (&A1 != &B1) && ... && (&An != &Bn).
   Set *COND_EXPR to a tree that is true when both the original *COND_EXPR
   and this new condition are true.  Treat a null *COND_EXPR as "true".  */

static void
vect_create_cond_for_unequal_addrs (loop_vec_info loop_vinfo, tree *cond_expr)
{
  const vec<vec_object_pair> &pairs
    = LOOP_VINFO_CHECK_UNEQUAL_ADDRS (loop_vinfo);
  unsigned int i;
  vec_object_pair *pair;
  FOR_EACH_VEC_ELT (pairs, i, pair)
    {
      tree addr1 = build_fold_addr_expr (pair->first);
      tree addr2 = build_fold_addr_expr (pair->second);
      tree part_cond_expr = fold_build2 (NE_EXPR, boolean_type_node,
					 addr1, addr2);
      chain_cond_expr (cond_expr, part_cond_expr);
    }
}

/* Create an expression that is true when all lower-bound conditions for
   the vectorized loop are met.  Chain this condition with *COND_EXPR.  */

static void
vect_create_cond_for_lower_bounds (loop_vec_info loop_vinfo, tree *cond_expr)
{
  const vec<vec_lower_bound> &lower_bounds
    = LOOP_VINFO_LOWER_BOUNDS (loop_vinfo);
  for (unsigned int i = 0; i < lower_bounds.length (); ++i)
    {
      tree expr = lower_bounds[i].expr;
      tree type = unsigned_type_for (TREE_TYPE (expr));
      expr = fold_convert (type, expr);
      poly_uint64 bound = lower_bounds[i].min_value;
      if (!lower_bounds[i].unsigned_p)
	{
	  expr = fold_build2 (PLUS_EXPR, type, expr,
			      build_int_cstu (type, bound - 1));
	  bound += bound - 1;
	}
      tree part_cond_expr = fold_build2 (GE_EXPR, boolean_type_node, expr,
					 build_int_cstu (type, bound));
      chain_cond_expr (cond_expr, part_cond_expr);
    }
}

/* Function vect_create_cond_for_alias_checks.

   Create a conditional expression that represents the run-time checks for
   overlapping of address ranges represented by a list of data references
   relations passed as input.

   Input:
   COND_EXPR  - input conditional expression.  New conditions will be chained
                with logical AND operation.  If it is NULL, then the function
                is used to return the number of alias checks.
   LOOP_VINFO - field LOOP_VINFO_MAY_ALIAS_STMTS contains the list of ddrs
	        to be checked.

   Output:
   COND_EXPR - conditional expression.

   The returned COND_EXPR is the conditional expression to be used in the if
   statement that controls which version of the loop gets executed at runtime.
*/

void
vect_create_cond_for_alias_checks (loop_vec_info loop_vinfo, tree * cond_expr)
{
  const vec<dr_with_seg_len_pair_t> &comp_alias_ddrs =
    LOOP_VINFO_COMP_ALIAS_DDRS (loop_vinfo);

  if (comp_alias_ddrs.is_empty ())
    return;

  create_runtime_alias_checks (LOOP_VINFO_LOOP (loop_vinfo),
			       &comp_alias_ddrs, cond_expr);
  if (dump_enabled_p ())
    dump_printf_loc (MSG_NOTE, vect_location,
		     "created %u versioning for alias checks.\n",
		     comp_alias_ddrs.length ());
}


/* Function vect_loop_versioning.

   If the loop has data references that may or may not be aligned or/and
   has data reference relations whose independence was not proven then
   two versions of the loop need to be generated, one which is vectorized
   and one which isn't.  A test is then generated to control which of the
   loops is executed.  The test checks for the alignment of all of the
   data references that may or may not be aligned.  An additional
   sequence of runtime tests is generated for each pairs of DDRs whose
   independence was not proven.  The vectorized version of loop is
   executed only if both alias and alignment tests are passed.

   The test generated to check which version of loop is executed
   is modified to also check for profitability as indicated by the
   cost model threshold TH.

   The versioning precondition(s) are placed in *COND_EXPR and
   *COND_EXPR_STMT_LIST.  */

class loop *
vect_loop_versioning (loop_vec_info loop_vinfo,
		      gimple *loop_vectorized_call)
{
  class loop *loop = LOOP_VINFO_LOOP (loop_vinfo), *nloop;
  class loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
  basic_block condition_bb;
  gphi_iterator gsi;
  gimple_stmt_iterator cond_exp_gsi;
  basic_block merge_bb;
  basic_block new_exit_bb;
  edge new_exit_e, e;
  gphi *orig_phi, *new_phi;
  tree cond_expr = NULL_TREE;
  gimple_seq cond_expr_stmt_list = NULL;
  tree arg;
  profile_probability prob = profile_probability::likely ();
  gimple_seq gimplify_stmt_list = NULL;
  tree scalar_loop_iters = LOOP_VINFO_NITERSM1 (loop_vinfo);
  bool version_align = LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT (loop_vinfo);
  bool version_alias = LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo);
  bool version_niter = LOOP_REQUIRES_VERSIONING_FOR_NITERS (loop_vinfo);
  poly_uint64 versioning_threshold
    = LOOP_VINFO_VERSIONING_THRESHOLD (loop_vinfo);
  tree version_simd_if_cond
    = LOOP_REQUIRES_VERSIONING_FOR_SIMD_IF_COND (loop_vinfo);
  unsigned th = LOOP_VINFO_COST_MODEL_THRESHOLD (loop_vinfo);

  if (vect_apply_runtime_profitability_check_p (loop_vinfo)
      && !ordered_p (th, versioning_threshold))
    cond_expr = fold_build2 (GE_EXPR, boolean_type_node, scalar_loop_iters,
			     build_int_cst (TREE_TYPE (scalar_loop_iters),
					    th - 1));
  if (maybe_ne (versioning_threshold, 0U))
    {
      tree expr = fold_build2 (GE_EXPR, boolean_type_node, scalar_loop_iters,
			       build_int_cst (TREE_TYPE (scalar_loop_iters),
					      versioning_threshold - 1));
      if (cond_expr)
	cond_expr = fold_build2 (BIT_AND_EXPR, boolean_type_node,
				 expr, cond_expr);
      else
	cond_expr = expr;
    }

  tree cost_name = NULL_TREE;
  profile_probability prob2 = profile_probability::always ();
  if (cond_expr
      && EXPR_P (cond_expr)
      && (version_niter
	  || version_align
	  || version_alias
	  || version_simd_if_cond))
    {
      cost_name = cond_expr = force_gimple_operand_1 (unshare_expr (cond_expr),
						      &cond_expr_stmt_list,
						      is_gimple_val, NULL_TREE);
      /* Split prob () into two so that the overall probability of passing
	 both the cost-model and versioning checks is the orig prob.  */
      prob2 = prob = prob.sqrt ();
    }

  if (version_niter)
    vect_create_cond_for_niters_checks (loop_vinfo, &cond_expr);

  if (cond_expr)
    {
      gimple_seq tem = NULL;
      cond_expr = force_gimple_operand_1 (unshare_expr (cond_expr),
					  &tem, is_gimple_condexpr_for_cond,
					  NULL_TREE);
      gimple_seq_add_seq (&cond_expr_stmt_list, tem);
    }

  if (version_align)
    vect_create_cond_for_align_checks (loop_vinfo, &cond_expr,
				       &cond_expr_stmt_list);

  if (version_alias)
    {
      vect_create_cond_for_unequal_addrs (loop_vinfo, &cond_expr);
      vect_create_cond_for_lower_bounds (loop_vinfo, &cond_expr);
      vect_create_cond_for_alias_checks (loop_vinfo, &cond_expr);
    }

  if (version_simd_if_cond)
    {
      gcc_assert (dom_info_available_p (CDI_DOMINATORS));
      if (flag_checking)
	if (basic_block bb
	    = gimple_bb (SSA_NAME_DEF_STMT (version_simd_if_cond)))
	  gcc_assert (bb != loop->header
		      && dominated_by_p (CDI_DOMINATORS, loop->header, bb)
		      && (scalar_loop == NULL
			  || (bb != scalar_loop->header
			      && dominated_by_p (CDI_DOMINATORS,
						 scalar_loop->header, bb))));
      tree zero = build_zero_cst (TREE_TYPE (version_simd_if_cond));
      tree c = fold_build2 (NE_EXPR, boolean_type_node,
			    version_simd_if_cond, zero);
      if (cond_expr)
        cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
				 c, cond_expr);
      else
        cond_expr = c;
      if (dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location,
			 "created versioning for simd if condition check.\n");
    }

  cond_expr = force_gimple_operand_1 (unshare_expr (cond_expr),
				      &gimplify_stmt_list,
				      is_gimple_condexpr_for_cond, NULL_TREE);
  gimple_seq_add_seq (&cond_expr_stmt_list, gimplify_stmt_list);

  /* Compute the outermost loop cond_expr and cond_expr_stmt_list are
     invariant in.  */
  class loop *outermost = outermost_invariant_loop_for_expr (loop, cond_expr);
  for (gimple_stmt_iterator gsi = gsi_start (cond_expr_stmt_list);
       !gsi_end_p (gsi); gsi_next (&gsi))
    {
      gimple *stmt = gsi_stmt (gsi);
      update_stmt (stmt);
      ssa_op_iter iter;
      use_operand_p use_p;
      basic_block def_bb;
      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
	if ((def_bb = gimple_bb (SSA_NAME_DEF_STMT (USE_FROM_PTR (use_p))))
	    && flow_bb_inside_loop_p (outermost, def_bb))
	  outermost = superloop_at_depth (loop, bb_loop_depth (def_bb) + 1);
    }

  /* Search for the outermost loop we can version.  Avoid versioning of
     non-perfect nests but allow if-conversion versioned loops inside.  */
  class loop *loop_to_version = loop;
  if (flow_loop_nested_p (outermost, loop))
    { 
      if (dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location,
			 "trying to apply versioning to outer loop %d\n",
			 outermost->num);
      if (outermost->num == 0)
	outermost = superloop_at_depth (loop, 1);
      /* And avoid applying versioning on non-perfect nests.  */
      while (loop_to_version != outermost
	     && (e = single_exit (loop_outer (loop_to_version)))
	     && !(e->flags & EDGE_COMPLEX)
	     && (!loop_outer (loop_to_version)->inner->next
		 || vect_loop_vectorized_call (loop_to_version))
	     && (!loop_outer (loop_to_version)->inner->next
		 || !loop_outer (loop_to_version)->inner->next->next))
	loop_to_version = loop_outer (loop_to_version);
    }

  /* Apply versioning.  If there is already a scalar version created by
     if-conversion re-use that.  Note we cannot re-use the copy of
     an if-converted outer-loop when vectorizing the inner loop only.  */
  gcond *cond;
  if ((!loop_to_version->inner || loop == loop_to_version)
      && loop_vectorized_call)
    {
      gcc_assert (scalar_loop);
      condition_bb = gimple_bb (loop_vectorized_call);
      cond = as_a <gcond *> (*gsi_last_bb (condition_bb));
      gimple_cond_set_condition_from_tree (cond, cond_expr);
      update_stmt (cond);

      if (cond_expr_stmt_list)
	{
	  cond_exp_gsi = gsi_for_stmt (loop_vectorized_call);
	  gsi_insert_seq_before (&cond_exp_gsi, cond_expr_stmt_list,
				 GSI_SAME_STMT);
	}

      /* if-conversion uses profile_probability::always () for both paths,
	 reset the paths probabilities appropriately.  */
      edge te, fe;
      extract_true_false_edges_from_block (condition_bb, &te, &fe);
      te->probability = prob;
      fe->probability = prob.invert ();
      /* We can scale loops counts immediately but have to postpone
	 scaling the scalar loop because we re-use it during peeling.

	 Ifcvt duplicates loop preheader, loop body and produces an basic
	 block after loop exit.  We need to scale all that.  */
      basic_block preheader = loop_preheader_edge (loop_to_version)->src;
      preheader->count = preheader->count.apply_probability (prob * prob2);
      scale_loop_frequencies (loop_to_version, prob * prob2);
      /* When the loop has multiple exits then we can only version itself.
	This is denoted by loop_to_version == loop.  In this case we can
	do the versioning by selecting the exit edge the vectorizer is
	currently using.  */
      edge exit_edge;
      if (loop_to_version == loop)
       exit_edge = LOOP_VINFO_IV_EXIT (loop_vinfo);
      else
       exit_edge = single_exit (loop_to_version);
      exit_edge->dest->count = preheader->count;
      LOOP_VINFO_SCALAR_LOOP_SCALING (loop_vinfo) = (prob * prob2).invert ();

      nloop = scalar_loop;
      if (dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location,
			 "reusing %sloop version created by if conversion\n",
			 loop_to_version != loop ? "outer " : "");
    }
  else
    {
      if (loop_to_version != loop
	  && dump_enabled_p ())
	dump_printf_loc (MSG_NOTE, vect_location,
			 "applying loop versioning to outer loop %d\n",
			 loop_to_version->num);

      unsigned orig_pe_idx = loop_preheader_edge (loop)->dest_idx;

      initialize_original_copy_tables ();
      nloop = loop_version (loop_to_version, cond_expr, &condition_bb,
			    prob * prob2, (prob * prob2).invert (),
			    prob * prob2, (prob * prob2).invert (),
			    true);
      /* We will later insert second conditional so overall outcome of
	 both is prob * prob2.  */
      edge true_e, false_e;
      extract_true_false_edges_from_block (condition_bb, &true_e, &false_e);
      true_e->probability = prob;
      false_e->probability = prob.invert ();
      gcc_assert (nloop);
      nloop = get_loop_copy (loop);

      /* For cycle vectorization with SLP we rely on the PHI arguments
	 appearing in the same order as the SLP node operands which for the
	 loop PHI nodes means the preheader edge dest index needs to remain
	 the same for the analyzed loop which also becomes the vectorized one.
	 Make it so in case the state after versioning differs by redirecting
	 the first edge into the header to the same destination which moves
	 it last.  */
      if (loop_preheader_edge (loop)->dest_idx != orig_pe_idx)
	{
	  edge e = EDGE_PRED (loop->header, 0);
	  ssa_redirect_edge (e, e->dest);
	  flush_pending_stmts (e);
	}
      gcc_assert (loop_preheader_edge (loop)->dest_idx == orig_pe_idx);

      /* Kill off IFN_LOOP_VECTORIZED_CALL in the copy, nobody will
         reap those otherwise;  they also refer to the original
	 loops.  */
      class loop *l = loop;
      while (gimple *call = vect_loop_vectorized_call (l))
	{
	  call = SSA_NAME_DEF_STMT (get_current_def (gimple_call_lhs (call)));
	  fold_loop_internal_call (call, boolean_false_node);
	  l = loop_outer (l);
	}
      free_original_copy_tables ();

      if (cond_expr_stmt_list)
	{
	  cond_exp_gsi = gsi_last_bb (condition_bb);
	  gsi_insert_seq_before (&cond_exp_gsi, cond_expr_stmt_list,
				 GSI_SAME_STMT);
	}

      /* Loop versioning violates an assumption we try to maintain during
	 vectorization - that the loop exit block has a single predecessor.
	 After versioning, the exit block of both loop versions is the same
	 basic block (i.e. it has two predecessors). Just in order to simplify
	 following transformations in the vectorizer, we fix this situation
	 here by adding a new (empty) block on the exit-edge of the loop,
	 with the proper loop-exit phis to maintain loop-closed-form.
	 If loop versioning wasn't done from loop, but scalar_loop instead,
	 merge_bb will have already just a single successor.  */

      /* When the loop has multiple exits then we can only version itself.
	 This is denoted by loop_to_version == loop.  In this case we can
	 do the versioning by selecting the exit edge the vectorizer is
	 currently using.  */
      edge exit_edge;
      if (loop_to_version == loop)
	exit_edge = LOOP_VINFO_IV_EXIT (loop_vinfo);
      else
	exit_edge = single_exit (loop_to_version);

      gcc_assert (exit_edge);
      merge_bb = exit_edge->dest;
      if (EDGE_COUNT (merge_bb->preds) >= 2)
	{
	  gcc_assert (EDGE_COUNT (merge_bb->preds) >= 2);
	  new_exit_bb = split_edge (exit_edge);
	  new_exit_e = exit_edge;
	  e = EDGE_SUCC (new_exit_bb, 0);

	  for (gsi = gsi_start_phis (merge_bb); !gsi_end_p (gsi);
	       gsi_next (&gsi))
	    {
	      tree new_res;
	      orig_phi = gsi.phi ();
	      new_res = copy_ssa_name (PHI_RESULT (orig_phi));
	      new_phi = create_phi_node (new_res, new_exit_bb);
	      arg = PHI_ARG_DEF_FROM_EDGE (orig_phi, e);
	      add_phi_arg (new_phi, arg, new_exit_e,
			   gimple_phi_arg_location_from_edge (orig_phi, e));
	      adjust_phi_and_debug_stmts (orig_phi, e, PHI_RESULT (new_phi));
	    }
	}

      update_ssa (TODO_update_ssa_no_phi);
    }

  /* Split the cost model check off to a separate BB.  Costing assumes
     this is the only thing we perform when we enter the scalar loop
     from a failed cost decision.  */
  if (cost_name && TREE_CODE (cost_name) == SSA_NAME)
    {
      gimple *def = SSA_NAME_DEF_STMT (cost_name);
      gcc_assert (gimple_bb (def) == condition_bb);
      /* All uses of the cost check are 'true' after the check we
	 are going to insert.  */
      replace_uses_by (cost_name, boolean_true_node);
      /* And we're going to build the new single use of it.  */
      gcond *cond = gimple_build_cond (NE_EXPR, cost_name, boolean_false_node,
				       NULL_TREE, NULL_TREE);
      edge e = split_block (gimple_bb (def), def);
      gimple_stmt_iterator gsi = gsi_for_stmt (def);
      gsi_insert_after (&gsi, cond, GSI_NEW_STMT);
      edge true_e, false_e;
      extract_true_false_edges_from_block (e->dest, &true_e, &false_e);
      e->flags &= ~EDGE_FALLTHRU;
      e->flags |= EDGE_TRUE_VALUE;
      edge e2 = make_edge (e->src, false_e->dest, EDGE_FALSE_VALUE);
      e->probability = prob2;
      e2->probability = prob2.invert ();
      e->dest->count = e->count ();
      set_immediate_dominator (CDI_DOMINATORS, false_e->dest, e->src);
      auto_vec<basic_block, 3> adj;
      for (basic_block son = first_dom_son (CDI_DOMINATORS, e->dest);
	   son;
	   son = next_dom_son (CDI_DOMINATORS, son))
	if (EDGE_COUNT (son->preds) > 1)
	  adj.safe_push (son);
      for (auto son : adj)
	set_immediate_dominator (CDI_DOMINATORS, son, e->src);
      //debug_bb (condition_bb);
      //debug_bb (e->src);
    }

  if (version_niter)
    {
      /* The versioned loop could be infinite, we need to clear existing
	 niter information which is copied from the original loop.  */
      gcc_assert (loop_constraint_set_p (loop, LOOP_C_FINITE));
      vect_free_loop_info_assumptions (nloop);
    }

  if (LOCATION_LOCUS (vect_location.get_location_t ()) != UNKNOWN_LOCATION
      && dump_enabled_p ())
    {
      if (version_alias)
        dump_printf_loc (MSG_OPTIMIZED_LOCATIONS | MSG_PRIORITY_USER_FACING,
			 vect_location,
                         "loop versioned for vectorization because of "
			 "possible aliasing\n");
      if (version_align)
        dump_printf_loc (MSG_OPTIMIZED_LOCATIONS | MSG_PRIORITY_USER_FACING,
			 vect_location,
                         "loop versioned for vectorization to enhance "
			 "alignment\n");

    }

  return nloop;
}
